Update Configuration to support log level filtering

[jaffinito]

Describe the story, please be clear on scope of the story.

• Configuration.xsd
  • Add a new attribute called “logLevelDenylist” to applicationLogging.forwarding.
  • Type: xs:string
  • Marked as optional
  • Documentation string something like “A comma-separated, case-insensitive, list of log levels that should be ignored and not sent up to New Relic.”
  • Add the license header back to Configuration.cs
• IConfiguration.cs
  • Add IEnumerable LogLevelDenylist
• DefaultConfiguration.cs
  • Add a new IEnumerable called “LogLevelDenylist” next to other “application logging” settings
  • Has an EnvironmentOverrides called “NEW_RELIC_APPLICATION_LOGGING_FORWARDING_LOG_LEVEL_DENYLIST”
  • Will need to string.Split the value with “.Split(new[] { StringSeparators.CommaChar, ' ' }, StringSplitOptions.RemoveEmptyEntries);”
• ReportedConfiguration.cs
  • Add IEnumerable LogLevelDenylist
  • Add a JsonProperty of “application_logging.log_level_denylist”
• tests/Agent/UnitTests/Core.UnitTest/DataTransport/ExhaustiveTestConfiguration.cs
  • Add IEnumerable LogLevelDenylist

Old PoC: https://github.com/newrelic/newrelic-dotnet-agent/compare/proto-log-level-deny-list

###Acceptance Criteria

• Have run xsd2code
• Confirm that new entry appears in Configuration.cs
• EnvironmentOverrides is setup properly
• Existing unit test pass
• New unit tests pass

[workato-integration]

https://issues.newrelic.com/browse/NR-140885