switch out chokidar for @parcel/watcher in dev cli (#148924)

After the recent changes to limit the dev-cli watcher to relevant
packages, the watcher started logging tons of unnecessary changes, and
in some cases breaking based on the state of the repo. I have seen this
happen with Chokidar before, and I'm not convinced we'll be able to fix
it, so instead I decided to swap it out with `@parcel/watcher`, which is
a conceptually simpler implementation that automatically batches changes
and watches an entire directory, rather than tons of unique
directories/files.

This new implementation is conceptually simpler, and because of the
design of the `@parcel/watcher` module I was pushed to reuse the
`RepoSourceClassifier` to determine if we should restart the server
based on a specific change. This means we now have a single source of
truth for test files and the like (the classifier will tell us if a file
is a test file, regardless of where it exists in the repo).

Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>

packages/kbn-repo-source-classifier/src/module_id.ts

@@ -16,4 +16,6 @@ export interface ModuleId {
   repoRel: string;
   /** info about the package the source file is within, in the case the file is found within a package */
   pkgInfo?: PkgInfo;
+  /** path segments of the dirname of this */
+  dirs: string[];
 }

packages/kbn-repo-source-classifier/src/repo_path.ts

@@ -60,10 +60,12 @@ export class RepoPath {
   }
 
   private segs: string[] | undefined;
-  /** get and cache the path segments from the repo-realtive versions of this path */
+  /** get and cache the path segments from the repo-realtive dirname of this path */
   getSegs() {
     if (this.segs === undefined) {
-      this.segs = Path.dirname(this.getRepoRel()).split('/');
+      this.segs = Path.dirname(this.getRepoRel())
+        .split('/')
+        .filter((s) => s !== '.');
     }
 
     return this.segs;

packages/kbn-repo-source-classifier/src/repo_source_classifier.ts

@@ -12,6 +12,10 @@ import { ModuleType } from './module_type';
 import { RANDOM_TEST_FILE_NAMES, TEST_DIR, TEST_TAG } from './config';
 import { RepoPath } from './repo_path';
 
+const STATIC_EXTS = new Set(
+  'json|woff|woff2|ttf|eot|svg|ico|png|jpg|gif|jpeg|html|md|txt|tmpl'.split('|').map((e) => `.${e}`)
+);
+
 export class RepoSourceClassifier {
   constructor(private readonly resolver: ImportResolver) {}
 
@@ -124,7 +128,7 @@ export class RepoSourceClassifier {
    * Determine the "type" of a file
    */
   private getType(path: RepoPath): ModuleType {
-    if (path.getExtname() === '.json') {
+    if (STATIC_EXTS.has(path.getExtname())) {
       return 'static';
     }
 
@@ -214,6 +218,7 @@ export class RepoSourceClassifier {
       type: this.getType(path),
       repoRel: path.getRepoRel(),
       pkgInfo: path.getPkgInfo() ?? undefined,
+      dirs: path.getSegs(),
     };
     this.ids.set(path, id);
     return id;