♻️ Merge Placement and Routing into Layout Synthesis

[ystade]

Description

This PR prepares the structure of the neutral atom compiler for upcoming projects, where the placement and routing stage will be performed in one step. This one step will be called layout synthesis. For the current implementation that splits both steps into separate stages, it provides a PlaceAndRouteSynthesizer that allows building a LayoutSynthesizer from separate Placement and Routing steps.

Checklist:

• The pull request only contains commits that are focused and relevant to this change.
• I have added appropriate tests that cover the new/changed functionality.
• I have updated the documentation to reflect these changes.
• I have added entries to the changelog for any noteworthy additions, changes, fixes, or removals.
• I have added migration instructions to the upgrade guide (if needed).
• The changes follow the project's style guidelines and introduce no new warnings.
• The changes are fully tested and pass the CI checks.
• I have reviewed my own code changes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[burgholzer]

This looks very clean. I only have some nitpick comments which should be addressed easily.