feat(GraphQL): Allow Multiple JWKUrls for auth.

[minhaj-shakeel]

Fixes GRAPHQL-1048.
This PR adds support for Passing multiple JWKUrls in the authorization header.

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This change is 

[abhimanyusinghgaur]

Reviewable status: 0 of 5 files reviewed, 3 unresolved discussions (waiting on @manishrjain, @minhaj-shakeel, @pawanrawal, and @vvbalaji-dgraph)

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graphql/authorization/auth.go, line 432 at r1 (raw file):

// FetchJWKs fetches the JSON Web Key set from a JWKUrl. It acquires a Lock over a as some of the
// properties of AuthMeta are modified in the process.

This part of the comment is stale now, can be removed:

It acquires a Lock over a as some of the properties of AuthMeta are modified in the process.

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graphql/schema/schemagen.go, line 409 at r1 (raw file):

Quoted 6 lines of code…

		for i := 0; i < len(metaInfo.authMeta.JWKUrls); i++ {
			fetchErr := metaInfo.authMeta.FetchJWKs(i)
			if fetchErr != nil {
				return nil, fetchErr
			}
		}

we should make 2 separate functions FetchJWK(i) and FetchJWKs()
FetchJWKs() will contain this for loop and use FetchJWK(i) internally?

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testutil/graphql.go, line 252 at r1 (raw file):

"jwkurls":

we should keep tests for both jwkurl and jwkurls. Let's let the original test be as it was, but to test jwkurls add another test.

[minhaj-shakeel]

Reviewable status: 0 of 5 files reviewed, 3 unresolved discussions (waiting on @abhimanyusinghgaur, @manishrjain, @pawanrawal, and @vvbalaji-dgraph)

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graphql/authorization/auth.go, line 432 at r1 (raw file):

Previously, abhimanyusinghgaur (Abhimanyu Singh Gaur) wrote…

// FetchJWKs fetches the JSON Web Key set from a JWKUrl. It acquires a Lock over a as some of the
// properties of AuthMeta are modified in the process.

This part of the comment is stale now, can be removed:

It acquires a Lock over a as some of the properties of AuthMeta are modified in the process.

Done.

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graphql/schema/schemagen.go, line 409 at r1 (raw file):

Previously, abhimanyusinghgaur (Abhimanyu Singh Gaur) wrote…

		for i := 0; i < len(metaInfo.authMeta.JWKUrls); i++ {
			fetchErr := metaInfo.authMeta.FetchJWKs(i)
			if fetchErr != nil {
				return nil, fetchErr
			}
		}

we should make 2 separate functions FetchJWK(i) and FetchJWKs()
FetchJWKs() will contain this for loop and use FetchJWK(i) internally?

Done.

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testutil/graphql.go, line 252 at r1 (raw file):

Previously, abhimanyusinghgaur (Abhimanyu Singh Gaur) wrote…

"jwkurls":

we should keep tests for both jwkurl and jwkurls. Let's let the original test be as it was, but to test jwkurls add another test.

Done.