Pregenerate bindings for aarch64-linux-android

[justsmth]

Issues:

Addresses #635

Description of changes:

See first commit: 77b6296

• Added logic to pregenerate bindings for aarch64-linux-android.
• Minor cleanup in how we invoke internal/external bindgen.
• Improve testing to confirm that pregenerated bindings are being used on platform we cross-compile to.

Call-outs:

• I bumped the version number to v0.24.2, but we might instead wait for a v0.25 release before publishing.

Testing:

• Successful workflow: https://github.com/aws/aws-lc-rs/actions/runs/12601981382

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and the ISC license.

[justsmth]

See: #649