fix: fix build process (#1594)

**Summary**
@clangsmith noticed that the build process was not working as expected when following instructions
here: https://github.com/sassoftware/vscode-sas-extension/blob/main/CONTRIBUTING.md#get-started.

This updates our process to copy files as part of rebuild, and cleanup files when starting build
scripts (to make sure we're not holding on to any stale assets)

**Testing**
- [x] Launched the extension using instructions in CONTRIBUTING.md
- [x] Ran `npm run vscode:prepublish` multiple times to make sure things worked
      (after removing dist files)
- [x] Ran `Launch client` followed by `npm run vscode:prepublish` to make sure nothing was broken

Author: scottdover

tools/build.mjs

@@ -1,7 +1,6 @@
 import concurrently from "concurrently";
 import esbuild from "esbuild";
 import fs from "fs";
-import path from "path";
 
 console.log("start");
 const dev = process.argv[2];
@@ -57,13 +56,38 @@ const browserBuildOptions = {
   },
 };
 
+const copyFiles = () => {
+  const foldersToCopy = [
+    {
+      src: "./server/node_modules/jsonc-parser/lib/umd/impl",
+      dest: "./server/dist/node/impl",
+    },
+    {
+      src: "./server/node_modules/pyright-internal-node/dist/packages/pyright-internal/typeshed-fallback",
+      dest: "./server/dist/node/typeshed-fallback",
+    },
+    {
+      src: "./server/src/python/sas",
+      dest: "./server/dist/node/typeshed-fallback/stubs/sas",
+    },
+    {
+      src: "./client/src/components/notebook/exporters/templates",
+      dest: "./client/dist/notebook/exporters/templates",
+    },
+  ];
+  foldersToCopy.forEach((item) =>
+    fs.cpSync(item.src, item.dest, { recursive: true }),
+  );
+};
+
 if (process.env.npm_config_webviews || process.env.npm_config_client) {
   const ctx = await esbuild.context(
     process.env.npm_config_webviews ? browserBuildOptions : nodeBuildOptions,
   );
   await ctx.rebuild();
 
   if (dev) {
+    copyFiles();
     await ctx.watch();
   } else {
     await ctx.dispose();
@@ -79,32 +103,7 @@ if (process.env.npm_config_webviews || process.env.npm_config_client) {
       name: "node",
     },
   ]);
-
-  await result.then(
-    () => {
-      const foldersToCopy = [
-        {
-          src: "./server/node_modules/jsonc-parser/lib/umd/impl",
-          dest: "./server/dist/node/impl",
-        },
-        {
-          src: "./server/node_modules/pyright-internal-node/dist/packages/pyright-internal/typeshed-fallback",
-          dest: "./server/dist/node/typeshed-fallback",
-        },
-        {
-          src: "./server/src/python/sas",
-          dest: "./server/dist/node/typeshed-fallback/stubs/sas",
-        },
-        {
-          src: "./client/src/components/notebook/exporters/templates",
-          dest: "./client/dist/notebook/exporters/templates",
-        },
-      ];
-      for (const item of foldersToCopy) {
-        fs.cpSync(item.src, item.dest, { recursive: true });
-        console.log(`${item.src} was copied to ${item.dest}`);
-      }
-    },
-    () => console.error("Assets failed to build successfully"),
+  await result.then(copyFiles, () =>
+    console.error("Assets failed to build successfully"),
   );
 }