[lldb][Process/FreeBSDKernelCore] Improve DoUpdateThreadList() (#183981)

This commit brings improves
`ProcessFreeBSDKernelCore::DoUpdateThreadList()` by porting features
from KGDB (`fbsd_kthr.c` specifically) and adding fixes. It includes:

1. Validate `stopped_cpus` before accessing `stoppcbs`
2. Check bounds for `mp_maxid`
3. Check errors when reading proc from memory
4. Detect new architectures from previous PRs (ppc64le, riscv64, arm)
which weren't handled correctly in `DoUpdateThreadList()`.

Fallbacks for finding offsets aren't ported since kernel exposes
hardcoded variables for offsets starting from FreeBSD 11. Fallbacks
aren't needed as LLDB 23 only supports FreeBSD 14 and later.

This commit also

Fixes: 2430410b7d879fce3db76c21bb8c60ed22abd0b5(#180669),
4a602c03ea050d7adf666d5a440164ca6f78707c(#180670),
3d251288df0642762d1bd86efa05e190005c2539(#180674)

---------

Signed-off-by: Minsoo Choo <minsoochoo0122@proton.me>
GitOrigin-RevId: 6dd52127a09564d0c3be12e2b26c83ceb43919c8