Common:
- Extended context proto with 2 methods: UnsetService and UnsetSlice

Context component:
- Added timestamp to logs
- Added methods UnsetService and UnsetSlice to Context client
- Implemented methods UnsetService and UnsetSlice in Context servicer
- Resolved conflict between service and slice entities with constraints and configrules

Common:
- renamed device type OPTICAL_LINE_SYSTEM to OPEN_LINE_SYSTEM
- added DATACENTER and EMULATED_DATACENTER device types.

Context:
- modified service constraints for test object to use nomenclature "metric[unit]"
- corrected ConstraintModel dump methods

Device:
- uncommented dump methods in database ContextModel and TopologyModel

OFC'22 / OECCPSC'22 tests:
- renamed device type OPTICAL_LINE_SYSTEM to OPEN_LINE_SYSTEM

WebUI:
OFC'22 / OECCPSC'22 tests:
- renamed device type OPTICAL_LINE_SYSTEM to OPEN_LINE_SYSTEM

- added exposition of redis-tests service for testing with Redis backend
- moved delete logic from Context Servicer to ORM components
- added support for constraints of different kinds

- added helper methods to copy/update grpc messages: config_rules, constraints, endpoint_ids, service_ids
-  extended Context ConstraintModel to support different types of constraints
- extended EndpointModel with get_endpoint helper method
- extended SliceModel to incorporate config rules

- Arranged .gitignore & .gitkeep files in common proto folder
- Created specific run_tests_locally script for Context component
- Moved imports from *.proto folder to common.proto folder
- Adapted common.tools.object_factory to new proto definitions for ConfigRule and Constraint
- Extended common.tools.type_checkers to new proto definitions for ConfigRule and Constraint
- Removed context's genproto.sh script
- Adapted Events generated to new timestamp data type
- Minor code and linting fixing

Common:
- Renamed common.metrics to common.rpc_method_wrapper
- Moved ServiceException to common.rpc_method_wrapper
- Implemented High-Level ORM methods to simplify Database handling

Context:
- Added flag to auto-populate fake data for testing purposes
- Added fake objects for testing purposes
- Minor corrections in ORM Database Models
- Reimplemented gRPC Servicer methods using HighLevel ORM helper methods
- Implemented complete unit testing of gRPC Servicer
- Added Message Broker to enable distribution of database events
- Implemented gRPC GetEvents methods
- Modified default config values to support larger number of persistent connections for events streaming
- Reimplemented Context REST Resource to re-use gRPC Servicer and prevent duplicating code

Automated Tests:
- Reactivated common and context unit tests

Context:
- ORM models completed and tested
- Deactivated unneeded code-linting warnings
- Improved coding of fast_hasher method
- Added test unit for fast_hasher method
- Improved organization and structure of test units

Context:
- Moved old code to separate folder (will be removed in future commit when development is completed)
- Solved bug with Link-EndPoint retrieval
- Implemented ServiceModel and related unit tests
- Moved helper methods to Tools.py file in database