Lapce needs generic LSP support #3865

Lapce needs generic LSP support, same as it's in Helix — just describe LS in the config and it just works, without any extra LS-wrappers plugins.

Pros:

• no plugins needed to use any LS in the Lapce
• nome more staled LS-plugins, no more version incompatibility (such as now rust-plugin and my nightly rust-analyzer)
• momentally huge ecosystem — any LS could be used in the editor with that generic LSP support.