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/lang/java/+lsp.el

@@ -0,0 +1,10 @@
+;;; lang/java/+lsp.el -*- lexical-binding: t; -*-
+;;;###if (featurep! +lsp)
+
+(def-package! lsp-java
+  :after-call java-mode
+  :init (add-hook 'java-mode-hook #'+lsp|init)
+  :config
+  ;; TODO keybinds
+  ;; TODO treemacs integration (?)
+  )