Add QuestDB to feat/monitoring branch

See merge request teraflow-h2020/controller!141

- Arranged commit before merge
- Replaced string-based timestamps by context.Timestamp
- Created helper functions to convert timestamps string from/to float
- Arranged requirements to meet dependencies of converter functions

# Conflicts:
#	src/monitoring/client/MonitoringClient.py
#	src/monitoring/proto/monitoring_pb2.py
#	src/monitoring/proto/monitoring_pb2_grpc.py
#	src/monitoring/service/MonitoringServiceServicerImpl.py
#	src/monitoring/tests/test_unitary.py

Adapted Service to common proto folder

See merge request teraflow-h2020/controller!128

- Added missing requirement in Service
- Removed unneeded requirements.txt in Context

- Moved imports from *.proto folder to common.proto folder
- Removed service's genproto.sh script
- Minor code and linting fixing
- Arranged requirements to accelerate Docker image creation
- Updated Dockerfile
- Arranged GitLab CI/CD pipeline
- Corrected usage of ConfigRules to use new custom ConfigRules
- Removed redundant/unused Tools file in service_handlers

Adapted Device(complete) & Monitoring(partial) to common proto folder

See merge request teraflow-h2020/controller!127

- arranged import of per-component proto to common proto

Common:
- Corrected Python package versions to prevent collisions with p4runtime

Context:
- Minor corrections in GitLab CI/CD pipeline

Device:
- Corrected Python package versions to prevent collisions with p4runtime

Monitoring:
- Arranged requirements to accelerate Docker image creation
- Corrected Python package versions to prevent collisions with p4runtime
- Updated Dockerfile
- Arranged GitLab CI/CD pipeline

Device:
- Removed obsoleted run_tests_locally-device.sh script
- Moved imports from *.proto folder to common.proto folder
- Removed device's genproto.sh script
- Minor code and linting fixing
- Arranged requirements to accelerate Docker image creation
- Updated Dockerfile
- Arranged GitLab CI/CD pipeline
- Corrected usage of ConfigRules to use new custom ConfigRules

Monitoring:
- Moved imports from *.proto folder to common.proto folder
- Removed monitoring's genproto.sh script

Adapted Context component to common proto folder

See merge request teraflow-h2020/controller!126

Merge branch 'develop' of https://gitlab.com/teraflow-h2020/controller into fix/context-proto-common

Policy/minimize policy ci runtime

See merge request teraflow-h2020/controller!125

# Conflicts:
#	proto/te.proto
#	src/common/tools/service/__init__.py
#	src/monitoring/service/MonitoringServiceServicerImpl.py

Modifications in the monitoring information model and skeleton of the methods in the server and client

- Arranged requirements to accelerate Docker image creation
- Updated Dockerfile
- Arranged GitLab CI/CD pipeline

- 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

Fix policy-related proto issues, unify in a single folder generated code for the different languages, and adapt generation scripts

See merge request teraflow-h2020/controller!124

- fixed issue with messages in policy.proto and context-policy.proto
- modified and unified script to generate Python code from proto files
- segregated script to generate UML code
- added/modified apropriate .gitignore files to prevent uploading generated code. It should be generated locally or during creation of Docker containers
- added symbolic link from common/proto to folder containing python generated code