nvim: Add superhtml lsp

Added html LSP 'superhtml' (only works for HTML5) and also use it for
formatting html (and 'shtml') files, replacing prettier.

Superhtml seems faster at formatting html and allows switching between
single-line and multi-line tags by adding/removing a space in front of
or behind an html tag, very nifty.

nvim/.config/nvim/lua/core/languages.lua

@@ -72,7 +72,7 @@ local languages = {
 		dap = { "delve" },
 	},
 	graphql = { format = { graphql = { "prettier" } } },
-	html = { format = { html = { "prettier", "rustywind" } } },
+	html = { lsp = { superhtml = {} }, format = { shtml = { "superhtml" }, html = { "superhtml", "rustywind" } } },
 	julia = { lsp = { julials = {} }, ts = { "julia" } },
 	json = {
 		lsp = { jsonls = {} },