Support ARM exception tables for stack tracing in `std.debug`

[mlugg]

Most ELF targets use DWARF CFI through the .eh_frame section for safely unwinding the call stack. However, ARM has its own mechanism, using the sections .ARM.exidx and .ARM.extab.

The format of these sections is defined by the document "Exception Handling ABI for the Arm Architecture". link to latest version at the time of writing

std.debug.SelfInfo---in particular the ELF implementation, std.debug.SelfInfo.Elf---should support interpreting this format on ARM to collect stack traces safely.

[alexrp]

https://codeberg.org/ziglang/zig/issues/30931