refactor(sbb-calendar): migrate component to lit

[MarioCastigliano]

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Issue

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• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)

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Changes

Changes in this pull request:

Browsers

I tested the build on the following browsers:

• Firefox Desktop
• Chrome Desktop
• Edge Desktop
• Safari Desktop
• Chrome Mobile
• Safari Mobile

Screen readers

I tested the build on the following browsers:

• JAWS Firefox Desktop
• JAWS Chrome Desktop
• NVDA Firefox Desktop
• NVDA Chrome Desktop
• VoiceOver Safari Desktop
• VoiceOver Chrome Desktop
• VoiceOver Safari Mobile
• Android Accessibility Suite Chrome Mobile

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
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Does this introduce a breaking change?

• Yes
• No

Other information

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Codecov Report

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[TomMenga]

Very good job, just some topic points

[jeripeierSBB]

LGTM, thanks!