Add test for multiple where directives

[cwhitby]

• Added or updated tests
• Added Docs for all relevant versions
• Updated the changelog

Related Issue/Intent

References #831

Changes

No code changes, only adding a test for applying multiple @where directives on the same field

Breaking changes

None

[spawnia]

@cwhitby I realized this problem is twofold. While i adapted the handling of BuilderDirective's to allow for multiple builders, the BaseDirective does not take into account that there may be more than one directive of the same name.

Thanks for the PR, i am working on a generalized fix.

[spawnia]

Actually, the GraphQL specification declares that directives must be unique per location. There is an ongoing RFC to allow repeatable directives: graphql/graphql-spec#472

[Jofairden]

@spawnia you should review this again, as afaik repeatable directives are now officially supported by the spec: https://github.com/graphql/graphql-wg/blob/master/notes/2019-10-10.md#repeatable-directives-ivan-10m

[spawnia]

@Jofairden thanks, I am aware. Added support in graphql-php for it myself and plan to enable repeatable directives in Lighthouse v5.

[spawnia]

@cwhitby the test is working now, since we changed some logic around that makes it function correctly. Also tried your original test 9a70046 (#834) and got a count of 0, should be correct?

Merging this for now.