Should be able to onboard a new Intent + initial Schema in a single call

[JoeCap08055]

Description

Currently, to onboard a new Intent + Schema requires multiple steps:

1. Create a proposal to create a new Intent
2. Approve/enact the proposal
3. Wait for the Intent to be created, get the IntentId
4. Create a second proposal to create a new Schema associated with the Intent
5. Approve/enact the proposal

This is a high-friction workflow that requires multiple touch points for people not actively involved in the development process. It would be more efficient if this process could be streamlined so that only one governance proposal is required; perhaps an extrinsic that creates an Intent + Schema in a single pass.