[FE] Improvements to "Create new role" Screen - Route to New Page

Use Case

Previously, the "Create New Role" was inline with the Role's table. This update includes a separate page to create a new role.

User experience goal

User Flow

1. Select "Create new role" on Roles and Permissions Page.
2. Route to new page "Create new role"
3. Breadcrumb shows "Create new role"
4. Title shows "Create new role"
5. The user is able to enter the "Name", "Description".
6. The user is able to select from "Base Level" options with the current selection (same as previous implementation).
7. The user is able to select from custom permissions with checkboxes (same as previous implementation)
8. All fields are required, add validation when custom role "Name" exists
9. Confirmation button is "Create role"

Visual Designs

Figma link and design issue

Current	Updates
No breadcrumb	Add breadcrumb for "New role"
No columnar layout	Update to one column form layout with header "New role". Reorder to name, description with helper text first. Add Permissions section with base role and description with link to documentation: https://docs.gitlab.com/ee/user/permissions.html#roles
Primary action button says "Create new role"	Change primary button copy to "Create role"
No validation when creating custom role with the same name	Add validation when role name exists
Description is optional	All form inputs are required.