Install LSP by default

[omentic]

With tooling being stabilized, NimLime should take cues from https://packagecontrol.io/packages/LSP-rust-analyzer and install an LSP configuration for nimlangserver by default.

[AmjadHD]

There is now an LSP plugin. It's not on Package Control yet.
I don't know if they should be merged to one plugin, but one certainly can recommend the other.