archived: LSP functionality is developed upstream

[jokeyrhyme]

• interested parties may follow new work elsewhere, per incorporate language server directly in the upstream nu executable #8
• the upstream PR is effectively glue-code between lsp-server and nu internals
• this project (nuls) is effectively glue-code between tower-lsp and nu --ide-... processes
• as such, most of the code in nuls fundamentally incompatible with the upstream work
• as I'm running out of time to complete on this project, and the value of any further work is questionable (seeing how short-lived it would be), I'm archiving nuls in favour of the upstream PR (and follow-up PRs)