This change refactors a bit to facilitate #650 by:
Replacing IKeyVaultService with more reusable interfaces ISignatureAlgorithmProvider and ICertificateProvider.
Simplifying the ISigner interface, so that signature algorithm provider-specific arguments don't need to be passed. Instead, signature providers can just request ISignatureAlgorithmProvider and/or ICertificateProvider services. The implementations of those services are currently Key Vault but could be something else.
CC @javierdlg, @clairernovotny
This change refactors a bit to facilitate #650 by:
IKeyVaultServicewith more reusable interfacesISignatureAlgorithmProviderandICertificateProvider.ISignerinterface, so that signature algorithm provider-specific arguments don't need to be passed. Instead, signature providers can just requestISignatureAlgorithmProviderand/orICertificateProviderservices. The implementations of those services are currently Key Vault but could be something else.