Add simpletimer extension

[zakinomiya]

Description

Screencast

Checklist

• I read the extension guidelines
• I read the documentation about publishing
• I ran npm run build and tested this distribution build in Raycast
• I checked that files in the assets folder are used by the extension itself
• I checked that assets used by the README are placed outside of the metadata folder

[raycastbot]

Congratulations on your new Raycast extension! 🚀

You can expect an initial review within five business days.

Once the PR is approved and merged, the extension will be available on our Store.

[pernielsentikaer]

Thanks for your contribution! Unfortunately, we have an extension in the store that is quite similar to yours. Did you see that one before submitting your extension?

We aim to keep similar extensions to a minimum and focus on enhancing the current ones in the store. You can read more about that here

I'm closing this PR for now, we can always open it again if needed

Feel free to contact me here or at Slack if you have any questions.