[eglot] Add support for eglot lsp client in emacs

- Update README
- Add eglot-specifics to cc, rs, py, hs
  removing unused lsp-mode packages when eglot is active
- Add eglot-specific bindings
- Add doctor warnings for debugger +lsp and +peek
- Add eglot-backed lookup-handlers
- Add flycheck checker using eglot for :checkers
  syntax users (using flycheck/flycheck#1676 and
  flycheck/flycheck#1592 discussion).
  This implementation is based on @marsam code, and uses recent
  Flycheck development in order to make the code smaller and
  easier to maintain.

modules/tools/lsp/autoload/common.el

@@ -0,0 +1,9 @@
+;;; tools/lsp/autoload/common.el -*- lexical-binding: t; -*-
+
+;;;###autodef
+(defun lsp! ()
+  "Dispatch to call the currently used lsp client entrypoint"
+  (interactive)
+  (if (featurep! +eglot)
+      (eglot-ensure)
+    (lsp-deferred)))