Update imports on file move

[jose-elias-alvarez]

Neovim just merged support for workspace/didChangeWatchedFiles. The method is not currently supported by typescript-language-server, and based on this issue, it seems that adding support upstream is unlikely.

We could add an option to register the client and use our existing rename file functionality to automatically update imports when files are moved (nvim-lsp-ts-utils had a primitive and unreliable version of this).