Submit mock secret

What does this MR do and why?

Implements #424458 (closed).

This is a frontend-only implementation for creating secrets, developed under the ci_tanukey_ui feature flag. The API is not available yet, so we're only mocking the GraphQL response here.

The following fields are required in order to submit a secret:

• Key
• Value
• Environment (* by default)
• Expiration

After submitting the secret, the user will be redirected to the secret details page. This page will be developed in future MRs, so it's just a blank page for now.

The access permission fields will also be implemented in #457380 instead. For now, they will be disabled in the form.

This is the final iteration for building the create secrets form on the frontend:

Iteration	MR
Make environments dropdown reusable	!138464 (merged)
Create base form with preview modal and key, value, description, expiration, and rotation fields	!146228 (merged)
Add environment dropdown	!147141 (merged)
Add access permission dropdowns, with user search	❌ Skipped for now
Integrate apollo and add form submission	👈 You are here!:

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Successful Submission	With Error
Screen_Recording_2024-04-26_at_14.59.24

How to set up and validate locally

1. Enable the ci_tanukey_ui feature flag for your project.
2. Visit <path-to-project-or-group>/-/secrets/new to view the form.
3. Fill up the form and verify that you can create a mock secret.