[clang] [clang][Interp] Implement inc/dec for IntegralAP (PR #69597)

[Timm Baeder via cfe-commits]

tbaederr wrote:

> FWIW, when the description for the PR says it can't be merged for some reason, it usually goes on the bottom of my review queue until those issues are addressed. It's difficult to accept known-broken code. :-(

Sorry, I forgot to re-enable the tests here. Now that https://reviews.llvm.org/D154581 has been merged, this works.

https://github.com/llvm/llvm-project/pull/69597