server doesn't watch for file add/remove

[jrieken]

• run tsserver
• run a command that removes/add TS files, like tsd install foo, git pull, etc

  the tsserver doesn't notice that change, https://github.com/Microsoft/TypeScript/blob/master/src/server/editorServices.ts#L881

[dbaeumer]

The interesting case here is the tsconfig.json which defines the project scope. Reloading the project in this case is an 'overkill' since all that needs to be done is to add/remove files to/from the project. IMO the tsserver should either handle that case correctly or should give up on file watching and rely on the editor to provide the file events.

[mhegazy]

@zhengbli is working on a fix for this as part of #4553 and #4643

[mhegazy]

@jrieken can you give this a try..