[flang][driver] Make --version and -version consistent with clang

This patch makes -version valid, and --version invalid, for
flang-new -fc1. The invocation
  flang-new --version
remains valid. This behaviour is consistent with clang
(and with clang -cc1 and clang -cc1as).

Previously, flang-new -fc1 accepted --version (as per Options.td), but
the frontend driver acutally checks for -version. As a result,
  flang-new -fc1 --version
triggered no action, emitted no message, and stalled waiting for
standard input.

Fixes #51438

Reviewed By: PeteSteinfeld, awarzynski

Differential Revision: https://reviews.llvm.org/D122542