lsp: add expand selection support (#674)

Using rust-analyzer's implementation with some minor tweaks

Author: sbdchd

Cargo.lock

@@ -60,6 +60,7 @@ snapbox = { version = "0.6.0", features = ["diff", "term-svg", "cmd"] }
 # local
 # we have to make the versions explicit otherwise `cargo publish` won't work
 squawk-github = { path = "./crates/squawk_github", version = "2.27.0" }
+squawk-ide = { path = "./crates/squawk_ide", version = "2.27.0" }
 squawk-lexer = { path = "./crates/squawk_lexer", version = "2.27.0" }
 squawk-parser = { path = "./crates/squawk_parser", version = "2.27.0" }
 squawk-syntax = { path = "./crates/squawk_syntax", version = "2.27.0" }

Cargo.toml

@@ -0,0 +1,20 @@
+[package]
+name = "squawk-ide"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+authors.workspace = true
+license.workspace = true
+
+[dependencies]
+squawk-syntax.workspace = true
+rowan.workspace = true
+line-index.workspace = true
+annotate-snippets.workspace = true
+log.workspace = true
+
+[dev-dependencies]
+insta.workspace = true
+
+[lints]
+workspace = true