Update the @tag and @key directives to be valid with the Federation v2 spec

[shawnhugginsjr]

Describe your PR and link to any relevant issues.
Here is the issue for this PR: #2370

I have:

• Added tests covering the bug / feature (see testing)
• Updated any relevant documentation (see docs)

[coveralls]

Coverage remained the same at 75.402% when pulling 68498a9 on shippio:master into 1acfea2 on 99designs:master.

[StevenACoffman]

Hi! Thanks! can you also update https://github.com/apollographql/apollo-federation-subgraph-compatibility specifically https://github.com/apollographql/apollo-federation-subgraph-compatibility/blob/main/implementations/gqlgen/go.mod