[bugfix][converter/core]: Enabled timer expression transformation

[jonathanlukas]

Camunda Community Hub Pull Request Template

Description

At the moment, the transformation of timer expressions is not possible.

This PR enables the transformation of timer expressions

Additional context

closes #289

Testing your changes

There are unit tests in place to assert the function of transforming a timer expression

Types of changes

• Bug fix (non-breaking change which fixes an existing open issue)
• New feature (non-breaking change which adds functionality to an extension)
• Breaking change (fix or feature that would cause existing functionality of an extension to change)
• Documentation update (changes made to an existing piece of documentation)

Checklist:

• My code adheres to the syntax used by this extension.
• My pull request requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the Camunda Community Hub documentation.
• I have read the Pull Request Process documentation.
• I have added or suggested tests to cover my changes suggested in this pull request.
• All new and existing CI/CD tests passed.
• I will /assign myself this issue, and add the relevant [issue labels] to it if they are not automatically generated by Probot.
• I will tag @camunda-community-hub/devrel in a new comment on this issue if 30 days have passed since my pull request was opened and I have not received a response from the extension's maintainer.

[github-actions]

Test Results

  26 files  +  26    26 suites  +26   2m 45s ⏱️ + 2m 45s
212 tests +212  212 ✔️ +212  0 💤 ±0  0 ❌ ±0 
330 runs  +330  330 ✔️ +330  0 💤 ±0  0 ❌ ±0 

Results for commit a09bd04. ± Comparison against base commit c5afd6a.

♻️ This comment has been updated with latest results.

[ingorichtsmeier]

We should clarify the attribute names.

[ingorichtsmeier]

Looks good to me, too.

Old -> JUEL
New -> FEEL

clarify a lot.