GraphQL - Move some big tests to small tests

[Premwoik]

This PR addresses MIM-1576 and moves tests that were using mocked schema to small tests.

Changes

• Move listener tests to small tests.
• Extract some useful functions to the graphql helper module.
• Introduce a new checkAuth field in the admin and the user schemas. This field allows users to ensure that they are authorized correctly.
• Add tests that check if GraphQL works correctly on the default MongooseIM configuration.
• Adapt mongooseimctl tests to use generic admin schema.

Fixed

• Removed default auth header from GraphiQL. It was useless for the user listener and its presence resulted in a wrong_creds error when loading documentation.

[codecov]

Codecov Report

Merging #3474 (1ec7a69) into feature/graphql (6d971fe) will decrease coverage by 0.01%.
The diff coverage is 83.33%.

@@                 Coverage Diff                 @@
##           feature/graphql    #3474      +/-   ##
===================================================
- Coverage            80.83%   80.82%   -0.02%     
===================================================
  Files                  424      427       +3     
  Lines                32566    32578      +12     
===================================================
+ Hits                 26324    26330       +6     
- Misses                6242     6248       +6     

Impacted Files	Coverage Δ
src/mongoose_graphql.erl	91.11% <ø> (ø)
src/mongoose_graphql/mongoose_graphql_enum.erl	33.33% <33.33%> (ø)
...ose_graphql/admin/mongoose_graphql_admin_query.erl	33.33% <100.00%> (+33.33%)	⬆️
...e_graphql/user/mongoose_graphql_user_auth_info.erl	100.00% <100.00%> (ø)
...goose_graphql/user/mongoose_graphql_user_query.erl	100.00% <100.00%> (ø)
src/mongoose_graphql/mongoose_graphql_default.erl	0.00% <0.00%> (-100.00%)	⬇️
src/mod_roster_riak.erl	81.53% <0.00%> (-15.39%)	⬇️
...goose_graphql/mongoose_graphql_cowboy_response.erl	72.72% <0.00%> (-9.10%)	⬇️
src/elasticsearch/mongoose_elasticsearch.erl	76.92% <0.00%> (-7.70%)	⬇️
src/mongoose_graphql/mongoose_graphql_errors.erl	87.50% <0.00%> (-3.13%)	⬇️
... and 14 more

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[mongoose-im]

small_tests_24 / small_tests / 1ec7a69
Reports root / small

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small_tests_23 / small_tests / 1ec7a69
Reports root / small

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dynamic_domains_pgsql_mnesia_24 / pgsql_mnesia / 1ec7a69
Reports root/ big
OK: 2737 / Failed: 0 / User-skipped: 186 / Auto-skipped: 0

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dynamic_domains_mssql_mnesia_24 / odbc_mssql_mnesia / 1ec7a69
Reports root/ big
OK: 2737 / Failed: 0 / User-skipped: 186 / Auto-skipped: 0

---

dynamic_domains_mysql_redis_24 / mysql_redis / 1ec7a69
Reports root/ big
OK: 2720 / Failed: 0 / User-skipped: 203 / Auto-skipped: 0

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dynamic_domains_pgsql_mnesia_23 / pgsql_mnesia / 1ec7a69
Reports root/ big
OK: 2737 / Failed: 0 / User-skipped: 186 / Auto-skipped: 0

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ldap_mnesia_23 / ldap_mnesia / 1ec7a69
Reports root/ big
OK: 1513 / Failed: 0 / User-skipped: 386 / Auto-skipped: 0

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internal_mnesia_24 / internal_mnesia / 1ec7a69
Reports root/ big
OK: 1598 / Failed: 0 / User-skipped: 301 / Auto-skipped: 0

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ldap_mnesia_24 / ldap_mnesia / 1ec7a69
Reports root/ big
OK: 1513 / Failed: 0 / User-skipped: 386 / Auto-skipped: 0

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pgsql_mnesia_24 / pgsql_mnesia / 1ec7a69
Reports root/ big
OK: 3124 / Failed: 0 / User-skipped: 195 / Auto-skipped: 0

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mysql_redis_24 / mysql_redis / 1ec7a69
Reports root/ big
OK: 3119 / Failed: 0 / User-skipped: 200 / Auto-skipped: 0

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elasticsearch_and_cassandra_24 / elasticsearch_and_cassandra_mnesia / 1ec7a69
Reports root/ big
OK: 1891 / Failed: 0 / User-skipped: 313 / Auto-skipped: 0

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mssql_mnesia_24 / odbc_mssql_mnesia / 1ec7a69
Reports root/ big
OK: 3124 / Failed: 0 / User-skipped: 195 / Auto-skipped: 0

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riak_mnesia_24 / riak_mnesia / 1ec7a69
Reports root/ big
OK: 1737 / Failed: 0 / User-skipped: 314 / Auto-skipped: 0