bug#69426: 29.2; Let eglot-rename suggest thing-at-point when renaming

[Chmouel Boudjnah <chmouel@chmouel.com>]

When using eglot-rename it asks for a new name (for the variable for
example) to rename to, it would be nice if there was a way to have the
current thing-at-point suggested as the new name.

Usually when renaming a variable you want to rename it to something that
is related to the current name with the defautl behavior you have to
type the current name manually.

I have a function like this that does it:

  (defun my-eglot-rename (newname)
    "Rename the current symbol to NEWNAME with initial input a."
    (interactive
     (list (read-from-minibuffer
            (format "Rename`%s' to: " (or (thing-at-point 'symbol t)
                                          "unknown symbol"))
            (or (thing-at-point 'symbol t) "") nil nil nil
            (symbol-name (symbol-at-point)))))
    (eglot--server-capable-or-lose :renameProvider)
    (eglot--apply-workspace-edit
     (jsonrpc-request (eglot--current-server-or-lose)
                      :textDocument/rename
`(,@(eglot--TextDocumentPositionParams)
                                             :newName ,newname))


which probably can work as advice to eglot-rename but it would be nice
if we can have this builtin.