JNI/JSSE: detect RSA_MIN_SIZE in tests, add Rsa.RSA_MIN_SIZE helper

[cconlon]

This PR detects the native RSA_MIN_SIZE value for use in JUnit tests. It also adds a static helper variable to com.wolfssl.wolfcrypt.Rsa called RSA_MIN_SIZE to easily use that value from Java.

This should fix failing Jenkins test: nightly-wolfcrypt-jni-ant-test-v2, which started failing after wolfSSL/wolfssl#7923 was merged.

[JacobBarthelmeh]

The code change looks good. Will a github actions test be added for building with smaller RSA key sizes supported (https://github.com/wolfSSL/wolfcrypt-jni/blob/master/.github/workflows/main.yml#L114) or will the test get added to internal Jenkins?

EDIT: To clarify, a test of hitting the smaller key sizes logic. Setting RSA_MIN_SIZE to something like the previous 512 bit size.

[cconlon]

@JacobBarthelmeh Great suggestion, I just added two GitHub Action tests (Ubuntu and OSX) that will build wolfcrypt-jni and run ant test using the wolfSSL configure --enable-jni CFLAGS="-DRSA_MIN_SIZE=1024".

Last successful runs of those on this PR are here:
https://github.com/wolfSSL/wolfcrypt-jni/actions/runs/11003415173/job/30593780628?pr=77
https://github.com/wolfSSL/wolfcrypt-jni/actions/runs/11003415173/job/30593779725?pr=77