Add rebuild rust sdk script

[kegsay]

This is currently fiddly because it isn't as simple as JS SDK. Notably:

• You need uniffi-bindgen-go
• You need the right branch of rust-sdk (ideally we would just use any commit sha and clobber the uniffi-rs dep)
• The bindings don't compile:
  • Needs // #cgo LDFLAGS: -lmatrix_sdk_ffi added (trivial in a script to do)
  • Needs import lines to be patched up (also trivial)
  • Needs type assertions on some FFI functions (hard to automate) Error as callback parameter does not compile NordSecurity/uniffi-bindgen-go#36
  • Needs package qualifier for RustBufferI (also hard to automate) Multiple crates sharing RustBufferI doesn't compile NordSecurity/uniffi-bindgen-go#43

We may need to fix these issue in uniffi-bindgen-go first before we can write a script to test a specific rust SDK SHA.