Language support for `gemtext`

This is a vscode extension for gemtext, via the LSP(Language Server Protocol).

Demo

vscode

Feature	LSP request	Description
`Diagnostic`	textDocument/diagnostic	Display error on invalid URLs, see gemtext-specification.
`Completion`	textDocument/completion	Type ? in the first column to trigger completions.
`Folding Range`	textDocument/foldingRange	Fold the preformatted(```) sections.
`Goto Definition`	textDocument/definition	Navigate between local `.gmi` files.
`Semantic Tokens`	textDocument/semanticTokens/full	Additional highlight support.