Add location field/metadata for manually setting the intended vault location

### Please agree to the following

- [X] I have searched [existing issues](https://github.com/cryptomator/hub/issues?q=) for duplicates
- [X] I agree to follow this project's [Code of Conduct](https://github.com/cryptomator/hub/blob/develop/.github/CODE_OF_CONDUCT.md)

### Summary

I'd like to let the users know where they can expect the vault to be located.

### Motivation

Since the vault template can be located _anywhere_, it would be great if users can at least be informed where the vault can be expected.

### Considered Alternatives

The description field could be used for that but a dedicated location field could improve usability and the location information can be shown differently.

### Anything else?

Maybe an admin should be able to manage preset locations so that users can choose sensible defaults.