Resolve "Fix libyang version in NBI component"

See merge request !230

- Updated README.md file
- Fixed libyang version in Dockerfile
- Fixed libyang version in install_requirements.sh
- Added folder libyang to global gitignore
- Added generation of .gitignore file for libyang/build

Resolve "(UBI) Error handling in ZTP component"

See merge request !228

refactor: change the Add , Delete , Update ztp services . Add exception handling for external services and remove unnecessary device==null exception handling. Create an internal exception handling mechanism for all the uni failures.

Merge branch 'feat/11-automate-end-to-end-tests-and-integrate-them-in-ci-cd-pipeline' into 'develop'

Resolve "Automate end-to-end tests and integrate them in CI/CD pipeline"

See merge request !216

- Added preliminary non-functional test scripts
- Renamed scripts and data files
- Added python code to test deployments
- Added CI/CD pipeline descriptor
- Added TFS descriptor file
- Added Dockerfile
- Added script to deploy node agents

- Added missing device activation test

- Added CI/CD pipeline descriptor
- Homogeneized Dockerfile

- Removed conftest settings as seem to collide with error reporting.
- Enforced re-build of docker images

- Disabled policy and ZTP HPAs

- Updated build commands to docker buildx
- Removed unneeded scripts
- Moved scripts to scripts folder

- Moved logs to after_script

- Deactivated ECOC'22 for troubleshooting

- Added logs to identify issue

- Deactivated deploy of WebUI

- Added logs to identify issue

- Reactivated end-to-end test
- Updated CI/CD pipeline descriptor

- Recovering manually-forced error used for testing end-to-end integration tests

- Testing failure condition

- Fixed set/update condition for components
- Removed unneeded log messages

- Cleanup for final testing

- Recovered default log levels to INFO
- Corrected Formatting of manifest files

- Disabled OFC'22 while resolving issues

- Added modification of log levels in manifests during deployment

- Deactivated unneeded log messages

- Corrected logic for processing a normal service request
- Corrected imports of ServicerImpl

- Corrected CI/CD pipeline descriptor deploy scripts

- Enabled re-build of components in OFC'22 & ECOC'22 tests

- Corrected composition of pathcomp request
- Minor cosmetic improvements

- Disable unneeded components