Use a generic versioning header

[Retzoh]

Is your feature request related to a problem? Please describe.

In #444 we moved the versioning spec to one file, used by all the APIs.
To avoid breaking changes in the Provider API, the Accept-content header was kept as application/vnd.mds.provider+json.

Describe the solution you'd like

With the 0.5.0 milestone, we can remove the .provider part of the header since it is now available for all the APIs.

The header would become application/vnd.mds+json.

Is this a breaking change

A breaking change would require consumers or implementors of the API to modify their code for it to continue to function (ex: renaming of a required field or the change in data type of an existing field). A non-breaking change would allow existing code to continue to function (ex: addition of an optional field or the creation of a new optional endpoint).

• Yes, breaking

Impacted Spec

For which spec is this feature being requested?

• agency
• policy
• provider

Describe alternatives you've considered

Leave the header as it is.

Additional context

None

[marie-x]

Sounds good to me

[schnuerle]

It looks like this change is now in dev, correct @Retzoh @Karcass? Can we close this issue now?

[marie-x]

I believe so.

[thekaveman]

Yes it is in there.

Closing.