[flang][driver] rename flang-new to flang (#110023)

This does a global rename from `flang-new` to `flang`. I also
removed/changed any TODOs that I found related to making this change.

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Co-authored-by: H. Vetinari <h.vetinari@gmx.com>
Co-authored-by: Andrzej Warzynski <andrzej.warzynski@arm.com>
GitOrigin-RevId: 06eb10dadfaeaadc5d0d95d38bea4bfb5253e077
1 file changed