Rename mqtt_channel::Message -> MqttMessage

[didier-wenzek]

Proposed changes

Make the distinction between tedge_actors::Message and mqtt_channel::MqttMessage explicit.

It was not really confusing as one is a struct and the other a trait, however the distinction helps to stress that actors such as the c8y converter are currently driven by MQTT messages. What I really want to change is the latter point: the c8y converter should not manipulate raw MQTT messages but parsed c8y + tedge messages. This PR is a first step in that direction.

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

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 90.56604% with 40 lines in your changes are missing coverage. Please review.

Project coverage is 76.6%. Comparing base (2ada77d) to head (1b569f8).
Report is 3 commits behind head on main.

Additional details and impacted files

Files	Coverage Δ
crates/common/mqtt_channel/src/channel.rs	66.6% <100.0%> (ø)
crates/common/mqtt_channel/src/connection.rs	55.5% <100.0%> (ø)
crates/common/mqtt_channel/src/tests.rs	86.8% <100.0%> (ø)
crates/common/mqtt_channel/src/topics.rs	85.9% <100.0%> (ø)
crates/common/tedge_utils/src/size_threshold.rs	87.5% <100.0%> (ø)
crates/core/c8y_api/src/json_c8y.rs	92.4% <100.0%> (ø)
...tedge_agent/src/tedge_operation_converter/actor.rs	49.8% <100.0%> (ø)
...tedge_agent/src/tedge_to_te_converter/converter.rs	92.6% <100.0%> (+0.3%)	⬆️
crates/core/tedge_api/src/entity_store.rs	93.1% <100.0%> (ø)
crates/core/tedge_api/src/health.rs	92.6% <100.0%> (ø)
... and 29 more

... and 4 files with indirect coverage changes

[github-actions]

Robot Results

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

[Bravo555]

Assuming I didn't miss anything that wasn't just the name change, LGTM