Exit with code 0 if service manager not present

[Ruadhri17]

Proposed changes

This PR changes exit code to 0 and prevents from running tedge components if service manager is not present.

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

#2172
#1953

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

Merging #2204 (8939c10) into main (81b9d51) will increase coverage by 0.0%.
Report is 10 commits behind head on main.
The diff coverage is 0.0%.

Additional details and impacted files

Files Changed	Coverage Δ
crates/core/tedge/src/cli/connect/command.rs	0.0% <0.0%> (ø)

... and 9 files with indirect coverage changes

[github-actions]

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
257	0	5	257	100	54m48.691s

[Bravo555]

The issue mentions displaying a warning to the user about software manager being unavailable and needing to manage services manually. I'd also be for including this, unless there is a reason not to.

[Ruadhri17]

it is included in new_bridge function so I left it there.