JDK 11 Build Header Support JWT Token Fix

[vivetiwa]

Summary

1. JWT token support - https://github.com/adobe/experience-platform-streaming-connect/issues/14
2. Optional headers support that could be sent to AEP endpoint - Could be use to support raw ingestion https://github.com/adobe/experience-platform-streaming-connect/issues/16
3. Upgrade gradle wrapper from 5.2.1 to 7.0 - jar could be build without installing java separately
4. Default java build to JDK 11, mark JDK 8 build as deprecated
5. Developer guide to use jwt token for authentication https://github.com/adobe/experience-platform-streaming-connect/issues/15

Related Issue

1. https://github.com/adobe/experience-platform-streaming-connect/issues/14
2. https://github.com/adobe/experience-platform-streaming-connect/issues/15
3. https://github.com/adobe/experience-platform-streaming-connect/issues/16

Changes

• JWT token support - https://github.com/adobe/experience-platform-streaming-connect/issues/14
• Optional headers support that could be sent to AEP endpoint - Could be use to support raw ingestion
• Upgrade gradle wrapper from 5.2.1 to 7.0 - jar could be build without installing java separately
• Default java build to JDK 11, mark JDK 8 build as deprecated
• Developer guide to use jwt token for authentication

Relevant Documentation

Please enter the links of any docs updated to reflect this change

How Has This Been Tested?

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• [x] I have signed the Adobe Open Source CLA.
• [ ] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.

[vivetiwa]

@nipunnair - Please review