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/scala/packages.el

@@ -1,6 +1,9 @@
 ;; -*- no-byte-compile: t; -*-
 ;;; lang/scala/packages.el
 
-(package! ensime)
 (package! sbt-mode)
 (package! scala-mode)
+
+(if (featurep! +lsp)
+    (package! lsp-scala)
+  (package! ensime))