file watcher: avoid fs.watch

[justinmk3]

nodejs fs.watch is unreliable, see #2381

• From https://github.com/paulmillr/chokidar#why :

  Node.js fs.watch ... Emits most changes as rename.

• os/platform-specific quirks

The reason we use fs.watch for cases like https://github.com/aws/aws-toolkit-vscode/pull/2381/files is because vscode's builtin watcher only works for files in a workspace folder. microsoft/vscode#3025

• Update: vscode watcher now supports out-of-workspace paths. API: Allow to use the file watcher for aribitrary folders microsoft/vscode#3025 (comment)
• Update (2023): vscode proposal for a new createFileSystemWatcher API Allow createFileSystemWatcher with custom exclude rules microsoft/vscode#169724

Proposal

• use https://github.com/paulmillr/chokidar or https://www.npmjs.com/package/fb-watchman instead of fs.watch
• Use vscode native support API: Allow to use the file watcher for aribitrary folders microsoft/vscode#3025
  • potential future advantage: this would presumably also work with the vscode virtual fs (VFS) layer Toolkit can run in web browser (e.g. vscode.dev), avoid nodejs APIs #2205 Support minimum-trust workspace #1823

[justinmk3]

Next vscode release will include this. microsoft/vscode#3025

Note:

For non-recursive watchers, no excludes will apply, but for recursive watchers, the same excludes apply that apply for workspace folder watching.