Remove FileSystemWatcher

[jolampi]

FileSystemWatcher is reported to cause relatively high CPU usage on multiroot workspaces.

Currently the editor only uses the watcher to detect if the .tmc folder is missing. This is a rare enough issue that it can be handled during the startup.

Remove the watcher here:

tmc-vscode/src/api/workspaceManager.ts

Line 47 in 317c1bf

private readonly _watcher: vscode.FileSystemWatcher;

Check that the .tmc folder is on the top of TMC workspace on startup and show a warning notification with one click fix to resolve the issue (since it causes a restart).