Rust wrapper: add wolfssl_wolfcrypt::curve25519 module

[holtrop-wolfssl]

Description

Rust wrapper: add wolfssl_wolfcrypt::curve25519 module

Testing

CI / unit tests

Checklist

• added tests
• updated/added doxygen
• updated appropriate READMEs
• Updated manual and documentation

[holtrop-wolfssl]

retest this please (hudson.remoting.ProxyException: java.nio.file.FileSystemException: /tmp/workspace/PRB-generic-config-parser@3@tmp/durable-60ba12fe: No space left on device)

[holtrop-wolfssl]

retest this please (No space left on device)

[devin-ai-integration]

🛟 Devin Lifeguard found 1 likely issues in this PR

• no-memory-leaks snippet: Before every early return Err(rc) that occurs after a successful wc_curve25519_init, call unsafe { sys::wc_curve25519_free(&mut wc_key) }; (or wrap the raw pointer in a helper struct implementing Drop) to ensure the allocation is released on all error paths.

@holtrop-wolfssl
please take a look at the above issues which Devin flagged. Devin will not fix these issues automatically.