Fix RSA-PSS signature verification and key generation issues

[cconlon]

This PR includes several fixes for RSA-PSS signature verification and key generation issues:

• Fix WolfCryptSignature.engineVerify() to correctly pass digest to rsaPssVerifyWithDigest() instead of incorrect digest as "full data"
• Add restriction for RSAPrivateCrtKey keys in WolfCryptSignature, similar to WolfCryptCipher, since native wolfCrypt requires CRT parameters for RSA ops.
• Improve RSASSA-PSS KeyPairGenerator compatibility with system KeyFactory
• Fix default SHA-256 salt length in WolfCryptPSSParameters

This PR includes JUnit tests to help prevent regression.

These fixes fix several of the OpenJDK SunJCE tests that were failing with wolfJCE running underneath.

[Copilot]

Pull Request Overview

This PR fixes several RSA-PSS signature verification and key generation issues in the wolfJCE provider to improve compatibility with OpenJDK SunJCE tests.

• Fixes WolfCryptSignature.engineVerify() to use correct digest parameter in rsaPssVerifyWithDigest() method
• Adds restriction for RSA private keys to require CRT parameters, similar to cipher implementation
• Implements dedicated RSASSA-PSS key pair generator with proper algorithm identification and system KeyFactory compatibility
• Corrects default SHA-256 salt length in PSS parameters

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
WolfCryptSignature.java	Fixes RSA-PSS signature verification logic and adds RSA private key validation
WolfCryptPssParameters.java	Updates default salt length to use SHA-256 digest size
WolfCryptProvider.java	Registers dedicated RSASSA-PSS key pair generator service
WolfCryptKeyPairGenerator.java	Implements RSASSA-PSS key generation with proper algorithm identification
WolfCryptSignatureTest.java	Adds comprehensive test for RSA-PSS multiple updates scenario
WolfCryptKeyPairGeneratorTest.java	Adds test for RSASSA-PSS key compatibility with system KeyFactory

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