Limit project name length

### Epic

_No response_

### Description

We currently have a list of 'banned' project names to avoid projects being created that have mislead DNS names that could clash or confuse users based on the platform URL they are given.

Maintaining a list isn't sustainable as we'll keep thinking of new words that should be on the list.

One way to 'reserve' 90% of words would be to introduce a minimum required length of project name.

- Is this a good idea?
- What length should we pick? 10 characters?
- What impact will this have on existing FF Cloud users?
- we can introduce this as a constraint on create time - so existing projects are unaffected. If/when we support changing name, any limit would apply on the new name.

### Acceptance Criteria

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