Use an eieio class to represent a server.

Use an eieio class to represent a server.

Allow clients of eglot.el to use specific server classes to represent
experimental servers.

Wherever you used to read "proc" you now probably read "server",
unless it's really the process properties that are sought after.

Should help Josh Elsasser implement pull request https://github.com/joaotavora/eglot/issues/6.

* eglot-tests.el (eglot--call-with-dirs-and-files)
(auto-detect-running-server, auto-reconnect, basic-completions)
(hover-after-completions): Adapt to server defclass instead of
proc.

* eglot.el
(eglot-server-programs): Add docstring.
(eglot--processes-by-project): Removed.
(eglot--servers-by-project): New variable.
(eglot--current-process): Removed.
(eglot--current-server): New function.
(eglot-server): New class.
(cl-print-object eglot-server): New method.
(eglot--current-process-or-lose): Removed.
(eglot--current-server-or-lose): New function.
(eglot--define-process-var): Remove.
(eglot--make-process): Rework.
(eglot--project-short-name): Remove.
(eglot--connect): Rework.
(eglot--interactive): Rework to allow custom classes.
(eglot, eglot-reconnect, eglot--process-sentinel)
(eglot--process-filter, eglot-events-buffer, eglot--log-event):
Rework.
(eglot--process-receive): Removed.
(eglot--server-receive): New function.
(eglot--send): Renamed from eglot--process-send.
(eglot--process-send): Removed.
(eglot-forget-pending-continuations)
(eglot-clear-status, eglot--call-deferred)
(eglot--server-ready-p, eglot--async-request, eglot--request)
(eglot--notify, eglot--reply, eglot--managed-mode-onoff)
(eglot--maybe-activate-editing-mode, eglot--mode-line-format):
Rework.
(eglot-shutdown): Rework.
(eglot-handle-notification *, eglot-handle-request *)
(eglot--register-unregister)
(eglot--signal-textDocument/didOpen)
(eglot--signal-textDocument/didClose)
(eglot--signal-textDocument/willSave)
(eglot--signal-textDocument/didSave)
(xref-backend-identifier-completion-table)
(xref-backend-definitions, xref-backend-references)
(xref-backend-apropos, eglot-completion-at-point)
(eglot-help-at-point, eglot-eldoc-function, eglot-imenu)
(eglot-rename)
(eglot--register-workspace/didChangeWatchedFiles)
(eglot--unregister-workspace/didChangeWatchedFiles)
(eglot--rls-probably-ready-for-p, eglot-handle-notification):
Rework (proc->server)

fixup

* eglot-tests.el (eglot--call-with-dirs-and-files)
(auto-detect-running-server, auto-reconnect, basic-completions)
(hover-after-completions):

* eglot.el (eglot--processes-by-project): Removed.
(eglot--servers-by-project): New variable.
(eglot--current-process): Removed.
(eglot--current-server): New function.