Increase code coverage

[smyrick]

📝 Description

Update the code coverage levels with more unit tests and update the maven settings to exclude the examples in the Jacoco reports

[codecov-io]

Codecov Report

Merging #376 into master will increase coverage by 17.53%.
The diff coverage is n/a.

@@              Coverage Diff              @@
##             master     #376       +/-   ##
=============================================
+ Coverage     78.23%   95.76%   +17.53%     
- Complexity      341      347        +6     
=============================================
  Files           132       98       -34     
  Lines          1470     1205      -265     
  Branches        236      213       -23     
=============================================
+ Hits           1150     1154        +4     
+ Misses          277       11      -266     
+ Partials         43       40        -3

Impacted Files	Coverage Δ	Complexity Δ
.../graphql/spring/execution/GraphQLContextFactory.kt	50% <0%> (-50%)	0% <0%> (ø)
.../graphql/sample/context/MyGraphQLContextFactory.kt
.../sample/directives/CustomDirectiveWiringFactory.kt
...e/datafetchers/CustomDataFetcherFactoryProvider.kt
...ample/directives/LowercaseSchemaDirectiveWiring.kt
...ediagroup/graphql/sample/query/EnvironmentQuery.kt
...diagroup/graphql/sample/mutation/WidgetMutation.kt
...le/exceptions/CustomDataFetcherExceptionHandler.kt
...in/com/expediagroup/graphql/sample/model/Animal.kt
...expediagroup/graphql/sample/query/DataAndErrors.kt
... and 31 more

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[dariuszkuc]

outside of this PR but maybe we should rename sample package to example?