Add tedgeUrl field for firmware command created by c8y-mapper

[rina23q]

Proposed changes

Cumulocity mapper adds tedgeUrl filed with the value: if the remoteUrl is c8y, using proxy url
otherwise, using the same url as remoteUrl

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

#2793

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA (in all commits with git commit -s)
• I ran cargo fmt as mentioned in CODING_GUIDELINES
• I used cargo clippy 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

[codecov]

Codecov Report

Attention: Patch coverage is 96.07843% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 76.6%. Comparing base (281fe69) to head (d55ddd2).
Report is 19 commits behind head on main.

Additional details and impacted files

Files	Coverage Δ
...s/c8y_mapper_ext/src/operations/firmware_update.rs	90.1% <96.0%> (+0.5%)	⬆️

... and 25 files with indirect coverage changes

[github-actions]

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
428	0	3	428	100	0s

[didier-wenzek]

Approved

[gligorisaev]

How to test:

1. Subscribe to the cmd topic, like:

te/device/main///cmd/firmware_update/+

2. Create a firmware operation from c8y cloud, and see what is printed out by 1
3. If you see tedgeUrl in the new firmware_update command payload, success