Implement declarative auth design for GraphQL service

[ldclakmal]

Purpose

This PR introduces the declarative auth design for GraphQL service.

Design: https://docs.google.com/document/d/1dGw5uUP6kqZNTwMfQ_Ik-k0HTMKhX70XpEA3tys9_kk/edit?usp=sharing

Fixes: ballerina-platform/ballerina-library#1336
Related to ballerina-platform/ballerina-library#584

Examples

@graphql:ServiceConfiguration {
    auth: [
        {
            oauth2IntrospectionConfig: {
                url: "https://localhost:9445/oauth2/introspect",
                tokenTypeHint: "access_token",
                scopeKey: "scp",
                clientConfig: {
                    secureSocket: {
                       cert: {
                           path: TRUSTSTORE_PATH,
                           password: "ballerina"
                       }
                    }
                }
            },
            scopes: ["write", "update"]
        },
        {
            fileUserStoreConfig: {},
            scopes: ["write", "update"]
        },
        {
            jwtValidatorConfig: {
                issuer: "wso2",
                audience: "ballerina",
                signatureConfig: {
                    trustStoreConfig: {
                        trustStore: {
                            path: TRUSTSTORE_PATH,
                            password: "ballerina"
                        },
                        certAlias: "ballerina"
                    }
                },
                scopeKey: "scp"
            },
            scopes: ["write", "update"]
        }
    ]
}
service /graphql on new graphql:Listener(9090) {
    isolated resource function get greeting() returns string {
        return "Hello World!";
    }
}

Checklist

• Linked to an issue
• Updated the changelog
• Added tests

[codecov]

Codecov Report

Merging #210 (8aff759) into master (cc8828c) will decrease coverage by 0.03%.
The diff coverage is 87.50%.

❗ Current head 8aff759 differs from pull request most recent head 37bbda7. Consider uploading reports for the commit 37bbda7 to get more accurate results

@@             Coverage Diff              @@
##             master     #210      +/-   ##
============================================
- Coverage     90.12%   90.08%   -0.04%     
  Complexity      204      204              
============================================
  Files            41       43       +2     
  Lines          1691     1796     +105     
  Branches        695      753      +58     
============================================
+ Hits           1524     1618      +94     
- Misses          153      164      +11     
  Partials         14       14              

Impacted Files	Coverage Δ	Complexity Δ
graphql-ballerina/annotations.bal	100.00% <ø> (ø)	0.00 <0.00> (ø)
graphql-ballerina/auth_types.bal	80.00% <80.00%> (ø)	0.00 <0.00> (?)
graphql-ballerina/auth_processor.bal	85.93% <85.93%> (ø)	0.00 <0.00> (?)
graphql-ballerina/annotation_processor.bal	100.00% <100.00%> (ø)	0.00 <0.00> (ø)
graphql-ballerina/engine.bal	82.69% <100.00%> (+0.69%)	0.00 <0.00> (ø)
graphql-ballerina/http_service.bal	100.00% <100.00%> (ø)	0.00 <0.00> (ø)
graphql-ballerina/modules/parser/types.bal	50.00% <0.00%> (ø)	0.00% <0.00%> (ø%)
graphql-ballerina/modules/parser/parser.bal	92.30% <0.00%> (+0.04%)	0.00% <0.00%> (ø%)
... and 1 more

---

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[shafreenAnfar]

LGTM

[ThisaruGuruge]

Added a couple of minor comments, but overall, LGTM.

[ThisaruGuruge]

Can't we directly return here?

Suggested change

	ListenerAuthConfig[] auth = <ListenerAuthConfig[]>serviceConfig?.auth;
	return auth;
	return <ListenerAuthConfig[]>serviceConfig?.auth;

[ThisaruGuruge]

Shall we use plural names for arrays? Like authConfigs?

[ThisaruGuruge]

Shall we add a test group for auth tests?

Suggested change

	@test:Config {}
	@test:Config {
	groups: ["auth"]
	}