Add basic LSP support

Still needs to be documented, but includes support for the following
languages:

+ C/C++/ObjC
+ Go
+ Java
+ Javascript
+ OCaml
+ PHP
+ Python
+ Ruby
+ Scala
+ Swift
+ HTML/CSS

Relevant to #460, #716, #1186

modules/tools/lsp/packages.el

@@ -0,0 +1,7 @@
+;; -*- no-byte-compile: t; -*-
+;;; tools/lsp/packages.el
+
+(package! lsp-mode)
+(package! lsp-ui)
+(when (featurep! :completion company)
+  (package! company-lsp))