[Support] Fix color handling in formatted_raw_ostream (#86700)

The color methods in formatted_raw_ostream were forwarding directly to
the underlying stream without considering existing buffered output. This
would cause incorrect colored output for buffered uses of
formatted_raw_ostream.

Fix this issue by applying the color to the formatted_raw_ostream itself
and temporarily disabling scanning of any color related output so as not
to affect the position tracking.

This fix means that workarounds that forced formatted_raw_ostream
buffering to be disabled can be removed. In the case of llvm-objdump,
this can improve disassembly performance when redirecting to a file by
more than an order of magnitude on both Windows and Linux. This
improvement restores the disassembly performance when redirecting to a
file to a level similar to before color support was added.

(cherry picked from commit c9db031c)