give committeeclash extra time

[SamStaijen]

there are quote a few committees participating in the CommitteeClash. It would be nice to have an optional .env variable by which we can modify the time the CommitteeClash gets shown on the radio.

Steps:

1. set up your local radio environment. Please follow the Readme.md, and if anything is unclear just tag me in this issue.
2. add the variable to your .env
3. add the variable name to vite-env.ts
4. modify the useTimer() method in committeeclash.tsx. For inspiration, look at Activities.tsx's useTimer(). Please note you want to change the duration, not the interval.
5. Now that you can change the duration of the committeeclash page, you want it to function normally if the .env variable is not set as well. For inspiration, please look at setCurrent() under the boardText-state in index.ts.
6. If this is all done, we need to do one more thing, and that is adding the .env variable to the sadserver repo, but that is easily done after the PR for this issue has been completed.

If you have any questions, please do not hasitate to ask!

Kusjes,
Sam