Proposed changes

Manually publish the service status of tedge-mapper-c8y to up when the built-in bridge connects to Cumulocity.

To ensure we always mark tedge-mapper-c8y as down when the mapper stops, the bridge's cloud connection sends the mapper service down command to Cumulocity as a last will message. This PR adds a corresponding message that is sent when the bridge connects to Cumulocity, meaning the service status is correctly marked as up after the mapper recovers from a network outage.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvement (general improvements like code refactoring that doesn't explicitly fix a bug or add any new functionality)
• Documentation Update (if none of the other choices apply)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Paste Link to the issue

#3075

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA (in all commits with git commit -s. You can activate automatic signing by running just prepare-dev once)
• I ran just format as mentioned in CODING_GUIDELINES
• I used just check as mentioned in CODING_GUIDELINES
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments