Trim some edges and add a bunch of boring rpc methods

Trim some edges and add a bunch of boring rpc methods

* eglot.el (eglot--connect): Don't call eglot--protocol-initialize.
(eglot--process-filter): Break long line.
(eglot--process-receive): Also pass id to handler if a server request.
(eglot--log): New helper.
(eglot-editing-mode): Manage before-revert-hook,
after-revert-hook, before-save-hook, after-save-hook.
(eglot--protocol-initialize): Removed.
(eglot--server-window/showMessage): Simplify.
(eglot--server-window/showMessageRequest)
(eglot--server-window/logMessage, eglot--server-telemetry/event):
New handlers.
(eglot--signal-textDocument/willSave)
(eglot--signal-textDocument/didSave): New notifications.
(eglot--signal-textDocument/didOpen)
(eglot--signal-textDocument/didClose): Check
eglot--buffer-open-count.
(eglot--buffer-open-count): New var.