Streamlining icons

Description

This PR updates the Formulus android icon as well as favicons used in various other places.
The icon graphics has been cleaned up and updated to be a round (completely circular) circle ;-)
The idea is to have the giraffe (I think we should call it "Girrna"?) be consistent in the visuals, and then we can swap out the graph/chart for whatever is relevant (e.g. a console for the CLI icon etc.).
Furthermore support for modern Android icons (with masking, foreground and background) is added..

closes #152

Type of Change

• Bug Fix
• New Feature / Enhancement
• Refactor / Code Cleanup
• Documentation Update
• Maintenance / Chore
• Other (please specify):

Component(s) Affected

• formulus (React Native mobile app)
• formulus-formplayer (React web app)
• synkronus (Go backend server)
• synkronus-cli (Command-line utility)
• portal
• Documentation
• DevOps / CI/CD
• Other:

Related Issue(s)

Closes/Fixes/Resolves:

Testing

• Unit tests added/updated
• Integration tests added/updated
• Manually tested
• Tested on multiple platforms (if applicable)
• Not applicable

Breaking Changes

• This PR introduces breaking changes
• This PR does NOT introduce breaking changes

If breaking changes, please describe migration steps:

Documentation Updates

• Documentation has been updated
• Documentation update is not required

Checklist

• Code follows project style guidelines
• All existing tests pass
• New tests added for new functionality
• PR title follows Conventional Commits format

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