Generalize package version

[pchila]

What does this PR do?

This PR improves elastic-agent version string handling during packaging and runtime by allowing generic semver-compliant version string handling and comparison.
It must be merged after #4491 has been merged to main

Why is it important?

This allows for more flexible version strings to be used in elastic-agent

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in ./changelog/fragments using the changelog tool
• I have added an integration test or an E2E test

Author's Checklist

• [ ]

How to test this PR locally

Related issues

• Requires Always launch more recent watcher #4491
• Closes Improve elastic agent version handling #4578

Use cases

Screenshots

Logs

Questions to ask yourself

• How are we going to support this in production?
• How are we going to measure its adoption?
• How are we going to debug this?
• What are the metrics I should take care of?
• ...

[mergify]

This pull request does not have a backport label. Could you fix it @pchila? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-v./d./d./d is the label to automatically backport to the 8./d branch. /d is the digit

NOTE: backport-skip has been added to this pull request.

[elastic-sonarqube]

Quality Gate passed

The SonarQube Quality Gate passed, but some issues were introduced.

3 New issues
0 Security Hotspots
88.2% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube

[mergify]

This pull request is now in conflicts. Could you fix it? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b generalize-package-version upstream/generalize-package-version
git merge upstream/main
git push upstream generalize-package-version