v1.19.0

AEA:

• Updates the aea init command to set the local as default registry and IPFS as default remote registry
• Updates the aea test packages to include the agent tests
• Introduces
  • aea packages command group to manage local packages repository
  • aea packages lock command to lock all available packages and create packages.json file
  • aea packages sync command to synchronize the local packages repository

Chores:

• Fix README header link
• Removes shebangs from non-script files
• Adds a command validator for docs and Makefile
• Deprecates the usage of hashes.csv to maintain packages consistency

Tests:

• Fixes test failures introduced on v1.18.0