[GlobalISel] LegalizationArtifactCombiner: Elide redundant G_AND

The legalizer currently generates lots of G_AND artifacts.
For example between boolean uses and defs there is always a G_AND with a mask of 1, but when the target uses ZeroOrOneBooleanContents, this is unnecessary.
Currently these artifacts have to be removed using post-legalize combines.
Omitting these artifacts at their source in the artifact combiner has a few advantages:
- We know that the emitted G_AND is very likely to be useless, so our KnownBits call is likely worth it.
- The G_AND and G_CONSTANT can interrupt e.g. G_UADDE/... sequences generated during legalization of wide adds which makes it harder to detect these sequences in the instruction selector (e.g. useful to prevent unnecessary reloading of AArch64 NZCV register).
- This cleans up a lot of legalizer output and even improves compilation-times.
AArch64 CTMark geomean: `O0` -5.6% size..text; `O0` and `O3` ~-0.9% compilation-time (instruction count).

Since this introduces KnownBits into code-paths used by `O0`, I reduced the default recursion depth.
This doesn't seem to make a difference in CTMark, but should prevent excessive recursive calls in the worst case.

Reviewed By: aemerson

Differential Revision: https://reviews.llvm.org/D159140