adding a screen before the race

[Quinstedt]

Added a screen before the race, showing the finish line so that the user knows what they need to find.

Close related issue : #97

☑️ Definition of Done checklist

• Meaningful title and valuable description in pull request
• Code change tested manually if not covered by automated tests
• Pull request linked to one or more issues/stories
• Acceptance criteria of the linked stories satisfied
• Code change comprehended by those who approved it
• State of target branch maintained or improved after the code change
• Go to MainActivityTest in the Android App and uncommit @test
  Run test manually. Add a picture of the test result in the comments.
  Comment @test again to avoid future problems with the CI

[faisal1201]

With this update, the player can have an idea of what the finish line looks like and what they are looking for. And some bugs have been fixed. Approval granted !

[faisal1201]

Test passing!