repl: remove deprecated repl.parseREPLKeyword() function

This removes the deprecated REPLServer.parseREPLKeyword function. It
is deprecated for a long time and should not provide any benefit to
users. To improve the maintainability of the REPL module, it's now
removed.

Signed-off-by: Ruben Bridgewater <ruben@bridgewater.de>

PR-URL: https://github.com/nodejs/node/pull/33286


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>