Don't treat on_activated as on_load if LSP has already loaded document
Don't treat on_activated as on_load if LSP has already loaded document

Every time you switched views, LSP would run fairly heavy checks:
* detect if you ran "Quick Switch Project"
* detect if more sessions can be started for the document

Both of these tasks are only relevant to views when they are first seen by LSP, so this commit gates it by checking the "lsp_active" setting on the view.

Breakage: Enabling a second server for already-opened views will likely not work - re-load window instead.

tomv564/LSP