3f5cc4c63 introduced some big changes to how Doom starts lsp-mode. I've
deferred much more of the work to upstream, but it:
1. lsp's errors no longer made sense (complaining about servers having
no automated install routine, despite having one).
2. Broke lsp support in indirect buffers (like org src/capture buffers).
So I half-reverted 3f5cc4c63 and added a +lsp-auto-install-servers
variable to make it optional (albeit opt-in).
`lsp-deferred` calls `lsp` and `lsp` seems to do something expensive
whether or not lsp-mode is already active. Over TRAMP, this is much too
expensive, so we no-op lsp-deferred if lsp-mode is already active.
