[llvm] [GlobalISel] Add G_BITCAST to computeKnownBits (PR #217841)

[Deepak Shirke via llvm-commits]

deepakshirkem wrote:

@chinmaydd I missed checking the issue tracker before starting this #216287 implements the same change. Closing in favour of that PR.

https://github.com/llvm/llvm-project/pull/217841