add mission badges

[Kandy-Peter]

In this pull request, I added the following functionalities

• Missions that the user has joined already shows a badge "Active Member" instead of the default "NOT A MEMBER"
• Button "Leave Mission" instead of the "Join Mission" button (as per design).

[tresorsawasawa]

STATUS: APPROVED 🟢 ✔️ ✔️ ✔️

Hi @Kandy-Peter
Your project is complete! There is nothing else to say other than... it's time to merge it
Congratulations! 🎉 👏 👏 💯

To highlight 🍾

• All linters are passing ✔️
• Good commit history ✔️
• Good PR description ✔️

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Cheers and Happy coding!👏👏👏

Feel free to leave any questions or comments in the PR thread if something is not 100% clear.

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