Improve project Id input

[raphaelts3]

This PR aims to implement the changes suggested on #26 doing the following changes:

• remove placeholder from the input;
• keep the Go! disabled, until a valid project Id is typed;
  • valid here means:
    • only digits;
    • gets 200 response when tested against https://trampoline.turbowarp.org/api/projects/${projectId}/; The usage of HEAD method is a slight optimization to get the minimal response, since this request might get re-done later if the user hits the Go! button;

If approved, this PR closes #26.

[pufferfish101007]

Hi, thank you for this.

I would rather not check for project existance via turbowarp trampoline before pressing go, as I'd prefer to hit any external services as little as possible.

Other than that, looks good.

[raphaelts3]

Thank for the quick review @pufferfish101007, so your suggestion is to just remove the external check and that's it? Or use a different extra check before enabling the Go!? I will also check the lint issues.

[pufferfish101007]

Yes, I'd rather just remove the external check.

The lint is not caused by your changes, so don't worry about it :)