Improvement: Redesign exercise screen & adjustments

[julian-wls]

Problem Description

Currently, the exercise view is quite unstructured compared to the iOS app. Points and build information are not as visible, and when holding the phone in landscape mode, scrolling through the web view becomes nearly impossible.

Changes

This PR introduces the following changes:

• The exercise information always shows the due date even if there is none
• the badge for dates have been removed and replaced with more accurate information
• the webview adjusts its height to the height of the content displayed making the whole view scrollable, not just the webview
• the participation not possible message has been moved outside the ExerciseActionButtons
• a link to the channel of the exercise has been added
• the ExerciseActionButton has been moved to always be next to the score information
• the result now shows the correct information
• many fixes and adjustments

Steps for testing

• browse through the exercise list (also check landscape mode) and verify the exercise list items are displayed as before
• click on different exercise and compare the score information and other available information with the web app, make sure it is identical
• check the result for a exercise that has one and verify it matches the one of the web app
• rotate the phone and make sure the view adjusts to landscape mode
• click on the channel link and verify that the destination is correct

Screenshots

Known issues

• in very rare cases the webview does not adjust to the correct height on the first try, but on the second try.
• after navigating to a channel using the link the back button does not work as expected.

The changes have been verified to work on tablets and foldables.

[FelberMartin]

Tested the functionality and both works and looks awesome. Especially the height adjusted webview improves usability by a lot!

Don't be frightened by the large number of code comments, most of them are just minor code style suggestions and refactoring oppportunities I found :)

[eylulnc]

This looks really good! 😊 Test cases ✅, and Martin's annotations already address everything. Once his requests are applied, it’s good to go for me.

[FelberMartin]

Lgtm now!