Made nullContextWidget scrollable

[Blueg00d]

Closes #1741

When an empty list was provided to the DefaultConsumer builder, he uses the nullContentWidget, which that it can't be pulled down, making the widget tree not scrollable. Therefore, it was impossible to refresh the page.

Review checklist

• Terms and conditions reflect the changes

View Changes

• Description has screenshots of the UI changes.
• Tested both in light and dark mode.
• New text is both in portuguese (PT) and english (EN).
• Works in different text zoom levels.
• Works in different screen sizes.

Performance

• No helper functions to return widgets are added. New widgets are created instead.
• Used ListView.builder for Long Lists.
• Controllers (TextEditingController, ...) are beeing disposed of in dispose() method.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60%. Comparing base (df5f88d) to head (4fe086b).
⚠️ Report is 1 commits behind head on develop.

❌ Your project check has failed because the head coverage (60%) is below the target coverage (70%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@           Coverage Diff           @@
##           develop   #1759   +/-   ##
=======================================
  Coverage       60%     60%           
=======================================
  Files            2       2           
  Lines           81      81           
=======================================
  Hits            48      48           
  Misses          33      33           

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[pedroafmonteiro]

Thanks for this! Just a few considerations:

• On my end, when there are no restaurants, the page scrolls a bit too much. This shouldn't happen. Consider using the same implementation as we have on the Lectures/Exams page (schedule_page.dart -> nullContentWidget).
• Also, while we're messing with the restaurant page, could you change how the nullContentWidget looks so it is more similar to the other ones? (with an illustration, title and description)? We're using this website to get illustrations: https://undraw.co/

If you need any help, don't hesitate on asking! Thanks again for your work!

[Blueg00d]

New nullContentWidget for the restaurant page (Portuguese Version):