XWIKI-9782: New Crypto Service API

- New PKIX modules to manage X.509 certificates
- Internal improvement to the signing API

(cherry-picked from commits
8e8ea2645c78654a6d39750644f01c862fa8ba09, 1cd70e152564ff39f6797f5f6715944da59e433a and 5d1192431ff2a23ca1d1c0fe20380027fb2123bc on master)