[llvm] [llvm-jitlink] Add optional index argument in jitlink-check stub_addr() expressions (PR #78369)

[Stefan Gränitz via llvm-commits]

weliveindetail wrote:

That's a great idea! I changed the stub index into a filter expression, so that we can match kinds flexibly like this:
```
stub_addr("foo.o", func, thumb)
stub_addr("foo.o", func, thumbv7)
stub_addr("foo.o", func, armv7_abs_le)
stub_addr("foo.o", func, .*v7_.*_le)
```

https://github.com/llvm/llvm-project/pull/78369