feat(jans-config-api): enhancements to saml api

[uprightech]

• Add endpoint to fetch metadata for trust relationship
• Change of method name(s) to lift ambiguity during openapi code generation

[uprightech]

Test cases

1. Get metadata file for an SP that doesn't exist

• Invoke endpoint jans-config-api/kc/saml/trust-relationship/sp-metadata-file/00000000-0000-0000-0000-000000000000
• Return code should be 404 , body should be message indicating the trust relationship was not found

2. Get metadata file for a SP that exists (file metadata source type)

• Create a new SP , making sure it's metadata source type is file. Note it's inum
• Invoke endpoint jans-config-api/kc/saml/trust-relationship/sp-metadata-file/<inum> where <inum> is the SP's inum
• Return code should be 200, mime type should be application/xml and body should be the metadata in xml

3. Get metadata file for a SP that exists but isn't a file metadata source type

• Create a new SP , making sure it's metadata source type is manual. Note it's inum
• Invoke endpoint jans-config-api/kc/saml/trust-relationship/sp-metadata-file/<inum> where <inum> is the SP's inum
• Return code should be 400 , body should be message indicating the trustrelationship metadata type isn't FILE