remove validation of optional service properties

[llorllale]

The sidetree spec mandates the inclusion of id, type, and endpoint in each service entry: https://identity.foundation/sidetree/spec/#add-service-endpoints.

Beyond those, it does not prescribe any limitation on additional fields that may be included. This check should therefore be removed.

[sandrask]

A month ago or so spec allowed only for "MUST" properties and @troyronda wanted to include additional properties only if they are on 'allowed' list. @troyronda Do you still want a check for properties added in add-service-endpoint patch or I should I remove check as @llorllale suggested?

[sandrask]

@troyronda any decisions on my comment above

[llorllale]

@sandrask @troyronda checks for specific fields outside those absolutely required by did-core (id, type, endpoint) would encumber extensions to did documents (ie. custom vocabularies that extend service entries).

[sandrask]

@llorllale I agree that removing restrictions is more flexible so I am for it @troyronda just has to confirm it is ok to remove allowed list (since it was his idea to create it)

[sandrask]

After discussion with @llorllale and @troyronda it has been decided to disable validation of optional service endpoint fields. New issue has been created #373