- Fixed composition of PolicyRule messages
- Added position of endpoints in Link, Service, and Slice.
- Added sort of endpoints according to their position.

- Added indexes recommended by Cockroach internal planner to boost performance
- Added extra foreign-key indexes to enhance constraint validation

- Added/Updated headers
- Added script to update copyright headers

- corrected unitary test order and one-by-one execution
- extractedunitary test constant to separate file
- added updated_at refresh for Service and Slice entities
- corrected return types for Connection entity
- prepared PolicyRule entity to raise events and corrected return types of methods

- extended grpc-to-enum tool to support arbitrary enum item names
- added PolicyRuleState enum model
- misc minor comment corrections
- misc import reorderings
- migrated Connection model and methods
- migrated PolicyRule model and methods
- removed unused files

- reorganized code spliting database models, enumerations, and operation methods
- separated unitary tests per entity and defined order between them
- separated unitary test for fasthasher
- modev old code to separate folder

- pre-merge cleanup of policy persistence

Lacks events.

Signed-off-by: mansoca <carlos.manso@cttc.es>