Add support for "v0" (non-legacy) Rust symbol mangling

[vorporeal]

Rust is changing their symbol mangling strategy; the new version is currently available via a compiler flag: -C symbol-mangling-version=v0.

See rust tracking issue here: rust-lang/rust#60705

We'd like to use this new symbol mangling format, but Sentry doesn't seem to quite demangle these properly:

Note in the above image that Sentry doesn't know which crate the stack frame is from, and is failing to strip (what appears to be) some hash from the crate name.