Unify initialization process for all editors

Right now, our LSP only requests settings when client is VSCode or NeoVim. To make matters worse, it requests *different* settings for these clients:

- for VSCode, it requests VSCode-specific about files and extensions,
- for NeoVim, it requests settings in scope `"Lua"`, and uses them as overrides for `.emmyrc`.

This PR aims to unify this behavior and make it easier for users to override settings without having to create `.emmyrc.json`. This is especially handy when you want to override a setting for a single project, but don't want to change project's `.emmyrc.json`. For example, switching documentation highlighting on per-project basis will become easier (see discussion in #665).

# Changes

- When client is VSCode, LSP will request settings under `"emmylua"` scope, as well as VSCode-specific settings mentioned above.

  I'll add relevant settings to the plugin settings page in a separate PR when this is merged; until then, these changes will not affect user experience.

- When client is NeoVim, LSP will request settings under `"emmylua"` scope. If there's no such scope, it will fall back to using the `"Lua"` scope.

  Currently, both LuaLs and EmmyLua use the same scope `"Lua"`. It works in NeoVim because options for every LSP server are independent. In VSCode, however, they all share the same namespace, meaning that we can't reuse `"Lua"`. I'd like to keep things consistent, hence this rename.

  I'll send a PR to update nvim-lspconfig's documentation for EmmyLua when this is merged.

- For any other client, LSP will request settings under `"emmylua"` scope.

  Currently, there are no clients that provide this scope (EmmyLua2 for Intellij doesn't provide any config scopes), so it shouldn't break anything, but it will provide future client implementations with a better way to override LSP configuration.

# Tests

Tested this with VSCode and NeoVim.

Author: taminomara

crates/emmylua_ls/src/handlers/initialized/client_config/default_config.rs

@@ -0,0 +1,63 @@
+use std::time::Duration;
+
+use log::info;
+use serde_json::Value;
+
+use crate::{context::ServerContextSnapshot, util::time_cancel_token};
+use emmylua_code_analysis::file_path_to_uri;
+
+use super::ClientConfig;
+
+pub async fn get_client_config_default(
+    context: &ServerContextSnapshot,
+    config: &mut ClientConfig,
+    scopes: Option<&[&str]>,
+) -> Option<()> {
+    let workspace_folders = context
+        .workspace_manager
+        .read()
+        .await
+        .workspace_folders
+        .clone();
+    let main_workspace_folder = workspace_folders.get(0);
+    let client = &context.client;
+    let scope_uri = main_workspace_folder.map(|p| file_path_to_uri(p).unwrap());
+
+    let mut configs = Vec::new();
+    let mut used_scope = None;
+    for scope in scopes.unwrap_or(&["emmylua"]) {
+        let params = lsp_types::ConfigurationParams {
+            items: vec![lsp_types::ConfigurationItem {
+                scope_uri: scope_uri.clone(),
+                section: Some(scope.to_string()),
+            }],
+        };
+        let cancel_token = time_cancel_token(Duration::from_secs(5));
+        let fetched_configs: Vec<_> = client
+            .get_configuration::<Value>(params, cancel_token)
+            .await?
+            .into_iter()
+            .filter(|config| !config.is_null())
+            .collect();
+        if !fetched_configs.is_empty() {
+            info!("found client config in scope {scope:?}");
+            configs = fetched_configs;
+            used_scope = Some(scope.to_string());
+        }
+    }
+
+    if let Some(used_scope) = used_scope {
+        info!(
+            "using client config from scope {used_scope:?}: {}",
+            serde_json::to_string_pretty(&configs)
+                .as_deref()
+                .unwrap_or("<failed to serialize json>")
+        );
+    } else {
+        info!("no client config found");
+    }
+
+    config.partial_emmyrcs = Some(configs);
+
+    Some(())
+}

crates/emmylua_ls/src/handlers/initialized/client_config/mod.rs

@@ -1,7 +1,7 @@
-mod neovim_config;
+mod default_config;
 mod vscode_config;
 
-use neovim_config::get_client_config_neovim;
+use default_config::get_client_config_default;
 use serde_json::Value;
 use vscode_config::get_client_config_vscode;
 
@@ -30,8 +30,10 @@ pub async fn get_client_config(
     };
     match client_id {
         ClientId::VSCode => get_client_config_vscode(context, &mut config).await,
-        ClientId::Neovim => get_client_config_neovim(context, &mut config).await,
-        _ => Some(()),
+        ClientId::Neovim => {
+            get_client_config_default(context, &mut config, Some(&["Lua", "emmylua"])).await
+        }
+        _ => get_client_config_default(context, &mut config, None).await,
     };
 
     config

crates/emmylua_ls/src/handlers/initialized/client_config/neovim_config.rs

@@ -1,10 +1,8 @@
-use std::{collections::HashMap, time::Duration};
-
-use serde::{Deserialize, Serialize};
-
-use crate::{context::ServerContextSnapshot, util::time_cancel_token};
-
 use super::ClientConfig;
+use crate::handlers::initialized::client_config::default_config::get_client_config_default;
+use crate::{context::ServerContextSnapshot, util::time_cancel_token};
+use serde::{Deserialize, Serialize};
+use std::{collections::HashMap, time::Duration};
 
 #[derive(Debug, Deserialize, Serialize)]
 struct VscodeFilesConfig {
@@ -17,6 +15,8 @@ pub async fn get_client_config_vscode(
     context: &ServerContextSnapshot,
     config: &mut ClientConfig,
 ) -> Option<()> {
+    get_client_config_default(context, config, None).await;
+
     let client = &context.client;
     let params = lsp_types::ConfigurationParams {
         items: vec![lsp_types::ConfigurationItem {