[flang] begin processing format strings

Move RoundingMode to Fortran.h

Always skip blanks outside character literals & Hollerith

Templatize

optimize repeat counts somewhat

Fix license punctuation, remove patch

Original-commit: flang-compiler/f18@4a0d39b0398974ade4367a5a96e11a90e853c18c
Reviewed-on: https://github.com/flang-compiler/f18/pull/927