cli: Update component crates descriptions

[Bravo555]

Proposed changes

Description of these crates is shown by clap in CLI help, so the descriptions were updated to make them more consistent.

• a trailing dot . was removed (looking at most popular Rust crates at https://lib.rs/std, none of those that have only a single sentence have a trailing dot)
• the descriptions were uncapitalized (they consist of a single sentence anyway and sometimes start with thin-edge)

Here's how the help text looks now:

Run thin-edge services and plugins

Usage: tedge run [OPTIONS] <COMMAND>

Commands:
  tedge-mapper              tedge-mapper translates thin-edge.io data model to c8y/az/aws data model
  tedge-agent               tedge-agent interacts with a Cloud Mapper and one or more Software Plugins
  c8y-firmware-plugin       thin-edge device firmware management for Cumulocity
  tedge-watchdog            tedge-watchdog checks the health of all the thin-edge.io components/services
  c8y-remote-access-plugin  thin-edge.io plugin for the Cumulocity IoT's Cloud Remote Access feature
  tedge-write               tee-like helper for writing to files which `tedge` user does not have write permissions to
  help                      Print this message or the help of the given subcommand(s)

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

• feat: Trigger tedge multicall with symlinks as well as sub-commands #3313 (review)

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

The descriptions could be improved further:

• the description starting with the name of the component is redundant; the name is already on the left of it, so it could be removed
• if the name of the component is removed, we could capitalize the sentence to be more consistent with what clap already does (help description is capitalized)
• a more structured and consistent indication of whether or not something is a plugin and what it entails

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Additional details and impacted files

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[github-actions]

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
551	0	2	551	100	1h32m42.360430999s

[reubenmiller]

Suggested change

	description = "thin-edge device firmware management for Cumulocity"
	description = "thin-edge.io device firmware management for Cumulocity"

[reubenmiller]

Suggested change

	description = "thin-edge.io plugin for the Cumulocity IoT's Cloud Remote Access feature"
	description = "thin-edge.io plugin for the Cumulocity Cloud Remote Access feature"