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/rust/config.el

@@ -5,6 +5,9 @@
   (set-docsets! 'rust-mode "Rust")
   (setq rust-indent-method-chain t)
 
+  (when (featurep! +lsp)
+    (add-hook 'rust-mode-hook #'+lsp|init))
+
   (map! :map rust-mode-map
         :localleader
         :prefix "b"
@@ -15,6 +18,7 @@
 
 
 (def-package! racer
+  :unless (featurep! +lsp)
   :after rust-mode
   :config
   (add-hook 'rust-mode-hook #'racer-mode)
@@ -27,4 +31,3 @@
   :when (featurep! :feature syntax-checker)
   :after rust-mode
   :config (add-hook 'rust-mode-hook #'flycheck-rust-setup))
-