Implement the Challenges tab on the Career page

[moonysolari]

• When clicking on the Challenges tab on the Career page, location tiles will correctly be shown just like on official.
• When clicking on said tiles, corresponding challenges will correctly be shown.
• This PR is fully compatible with but does not depend on Update season 1 challenges and add challenges for the rest of the locations #77, including sniper missions.
• Escalation challenges are not hooked to the corresponding escalations #78 also affects this PR, such that no challenges pertaining to escalation missions work, including the Dartmoor Garden Show.