Add more `worktop/jwt` utilities

[lukeed]

Signers

Note: The ECDSA and HMAC families are considered ideal.
The missing PS* family (RSASSA-PSS + SHA-256|384|512) are discouraged/legacy.

• HS256, HS384, HS512
• ES256, ES384, ES512
• RS256, RS384, RS512
• PS256, PS384, PS512

Chores

• factory.verify tests

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Encryptors MAYBE

Note: These are MAYBE & will probably be added based on demand.

• RSA-OAEP + (A128CBC-HS256, A128CBC-HS512, A128GCM, A256GCM)
• RSA-OAEP-256 + (A128CBC-HS256, A128CBC-HS512, A128GCM, A256GCM)
• ...