Re #8573 - Added some CertificateService tests and improved CryptographyService tests of methods that extract public keys
Re #8573 - Implemented extract_public_key_from_certificate
Re #8573 - Added get_public_key method to KeyService that extracts a public key from a private key
Re #8569 Prepared services for dependency injection
Re #8472 - Added missing docstrings to KeyService and CertificateService classes
Re #8472 - Added KeyService.delete test and renamed a test suite
Applied a small change to the KeyService.get_keys method
Re #8472 - Implemented KeyService