Inline site and scanner profile creation
#### Problem
There is a lot of set-up required for on-demand scans. To create a scan from scratch, a user has to visit three separate screens to actually get the scan running (`create a scanner profile`, `create a site profile`, and `new on-demand scan`).
#### Proposal
We should allow users to create site and scanner profiles inline while on the `New DAST scan` page.
#### Designs
Implementation issue for design: https://gitlab.com/gitlab-org/gitlab/-/issues/299472

📽 [Video walkthrough](https://www.loom.com/share/8fcc1cde7fec4d988cbb1307ee13bd6b)
#### Implementation Plan
| Task # | Issue | Description | Department |
|--------|-------|-------------|------------|
| 1 | https://gitlab.com/gitlab-org/gitlab/-/issues/325238 | Make scanner profile form composable & reusable | gitlab~3412464 |
| 2 | https://gitlab.com/gitlab-org/gitlab/-/issues/325239 | Make site profile form composable & reusable | gitlab~3412464 |
| 3 | https://gitlab.com/gitlab-org/gitlab/-/issues/325250 | Add inline forms support in Profile Selector Component | gitlab~3412464 |
| 4 | https://gitlab.com/gitlab-org/gitlab/-/issues/241363 | Update GraphQL mutation to return complete payload | ~backend
| 5 | https://gitlab.com/gitlab-org/gitlab/-/issues/325251 | Update Documentation | gitlab~2278655 |
Notes:
- We may need to update GraphQL cache manually
- It might not be required if https://gitlab.com/gitlab-org/gitlab/-/issues/241363 is implemented
- Add more test coverage (related epic https://gitlab.com/groups/gitlab-org/-/epics/5640)
- Add feature spec for On-demand Scans form
- Creating standalone site / scanner profiles (done)
- Check the redirection logic (done)
- Check the Profile Library to contain the newly created profile
epic