Add instance name validation to frontend

There is a list of reserved instance names that the backend prevents a user from selecting when creating an instance. This list is currently [here](https://github.com/FlowFuse/flowfuse/blob/571484aa89d9050088ccbe9c1927e5072f314092/forge/db/models/Project.js#L22)

The frontend should prevent a user from submitting the form with any of these reserved names entered.

- [ ] move the list to `forge/lib/reservedNames.js` - so it can be required from the frontend (as we do with `builtInModules.js`)
- [ ] Update the create instance form to use this list and provide suitable feedback to the user if they enter a reserved name