core: Add examples and assembly tests for abort_immediate

[tgross35]

This isn't the most complicated function, but it currently isn't used
anywhere in-tree (typically intrinsics::abort is used instead) and
there are no examples or tests. Copy the examples from abort since
this should behave similarly, and also cover it in an assembly test. We
don't really need the assembly check for any guarantees but it is handy
to reference what the intrinsic actually does, and will let us know if
anything changes.

I also added tests for breakpoint on more platforms since these were
easy to do together.

Tracking issue: #154601

[rustbot]

r? @JonathanBrouwer

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[tgross35]

r? libs

[tgross35]

My scratch space for seeing what the various arches do https://rust.godbolt.org/z/Gs9jKPG7x

[tgross35]

@bors try jobs=test-x86_64-gnu-nopt,test-various,test-x86_64-gnu-llvm-22-*

[tgross35]

@bors try jobs=test-x86_64-gnu-nopt,test-various,test-x86_64-gnu-llvm-22-*

[rust-bors]

☀️ Try build successful (CI)
Build commit: 37b4513 (37b4513e2f97ccce286b5cd75747efaa239f81a1)
Base parent: 837b18a (837b18aae097503892d7aab6c7ddce332a991a21)

[rustbot]

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.