add support for aarch64 windows unwinding information

[froydnj]

We have a patch in bug 1529355 for interpreting aarch64 unwind information and emitting the appropriate bits in breakpad symbol files. We haven't landed it yet because clang-cl was producing bogus unwind information until clang 9...which we are just about to enable, I think?

I think I have a slightly updated patch that fixes some of the breakage that resulted from landing the patch; I'll try to get that uploaded to the bug.

[calixteman]

We should probably rewrite your patch in rust and split it:

• one part in https://github.com/m4b/goblin/blob/master/src/pe/exception.rs to read and parse unwind code
• and a second part in https://github.com/getsentry/symbolic/blob/master/minidump/src/cfi.rs to generate CFI informations from unwind operations got from the pe.

[gabrielesvelto]

Symbolic has had support for this for a while, and consequently we've had it in dump_syms too.