Cherry pick upstream APInt fixes

[vladimirradosavljevic]

Some of the fixes are merged in #630 , but the idea is to revert that PR and to cherry pick upstream fixes to simplify rebase.
Upstream fixes for this issue:

PRs:

1. [APInt] Fix APInt constructions where value does not fit bitwidth (NFCI) llvm/llvm-project#80309
2. [SelectionDAG][X86] Add SelectionDAG::getSignedConstant and use it in a few places. llvm/llvm-project#104555

Commits:

1. llvm/llvm-project@c876761 + llvm/llvm-project@3512bcc
2. llvm/llvm-project@dc831e8
3. llvm/llvm-project@246c236
4. llvm/llvm-project@3b27fce
5. llvm/llvm-project@06f64e8
6. llvm/llvm-project@73d835c
7. llvm/llvm-project@53c41f9
8. llvm/llvm-project@4d97ad5
9. llvm/llvm-project@7990a7e
10. llvm/llvm-project@adb4cfe
11. llvm/llvm-project@ce128d8 + llvm/llvm-project@5d28678
12. llvm/llvm-project@46fb225 + llvm/llvm-project@afa0f53

[akiramenai]

Done in #693