[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.el

@@ -1,53 +0,0 @@
-;;; feature/lsp/autoload.el -*- lexical-binding: t; -*-
-
-;;;###autodef
-(defun set-lsp-priority! (client priority)
-  "Change the PRIORITY of lsp CLIENT."
-  (require 'lsp-mode)
-  (if-let (client (gethash client lsp-clients))
-      (setf (lsp--client-priority client)
-            priority)
-    (error "No LSP client named %S" client)))
-
-;;;###autodef
-(defalias 'lsp! #'lsp-deferred)
-
-;;;###autoload
-(defun +lsp/uninstall-server (dir)
-  "Delete a LSP server from `lsp-server-install-dir'."
-  (interactive
-   (list (read-directory-name "Uninstall LSP server: " lsp-server-install-dir nil t)))
-  (unless (file-directory-p dir)
-    (user-error "Couldn't find %S directory" dir))
-  (delete-directory dir 'recursive)
-  (message "Uninstalled %S" (file-name-nondirectory dir)))
-
-;;;###autoload
-(defun +lsp/switch-client (client)
-  "Switch to another LSP server."
-  (interactive
-   (progn
-     (require 'lsp-mode)
-     (list (completing-read
-            "Select server: "
-            (or (mapcar #'lsp--client-server-id (lsp--find-clients))
-                (user-error "No available LSP clients for %S" major-mode))))))
-  (require 'lsp-mode)
-  (let* ((client (if (symbolp client) client (intern client)))
-         (match (car (lsp--filter-clients (lambda (c) (eq (lsp--client-server-id c) client)))))
-         (workspaces (lsp-workspaces)))
-    (unless match
-      (user-error "Couldn't find an LSP client named %S" client))
-    (let ((old-priority (lsp--client-priority match)))
-      (setf (lsp--client-priority match) 9999)
-      (unwind-protect
-          (if workspaces
-              (lsp-workspace-restart
-               (if (cdr workspaces)
-                   (lsp--completing-read "Select server: "
-                                         workspaces
-                                         'lsp--workspace-print
-                                         nil t)
-                 (car workspaces)))
-            (lsp-mode +1))
-        (setf (lsp--client-priority match) old-priority)))))