Use Craft built-in for actions and alerts/success

[kabel]

Also includes bug fixes for

• Fixing the metadata breadcrumb URL in mutli-site environments
• Allow site and keychain fields to be unset (removed from database) where form and validation allows

[kabel]

Here are some annotated screenshots highlighting the template changes made:

• A: Using Craft 4 formActions variable to handle provider actions Save and continue, disable, delete
• B: Add a clearer divider below the tab switched container
• C: Clean up the layout (margins) around the Key Pairs instructions
• D: Use Craft 4 field layout classes to make the keypair inputs side-by-side

• E: Update the markup of the Copy to clickboard provider Metadata XML field to be more accessible to follow other Craft patterns
• F: Removed the disabled attribute from readonly fields and instead remove the name attribute when a field should not be submitted. This should improve accessibility (disabled text is hard to read) and user experience with manual copying/selecting
• G: Removed custom styles for form headings in Bindings (hard to read)
• H: Allow a provider to be explicitly assign the Control Panel without having to manually create a (disabled) site that shares the same base URL as the Control Panel. This should help with folks that are using either headless or dedicated domains (null cpTrigger) in their Craft 4 configuration. This special (null) site is offset from the normal frontend sites by a disabled/invalid ---- divider option.

Assigning a provider to the Control Panel works by

1. Leaving the site null (default) in the database
2. Registering the login-related SSO endpoints for control panel requests too

• Y: Remove custom styles from the provider list (readability, consistency)
• Z: Expand the tables to fill the container

• R: In the provider form, for the key pair dropdown, add a label for records that are missing a label in the database. Labeled as (Untitled: #)

• P: Update heading styles in the setup meta section
• Q: Clean up some styles on the setup page for accessible headings

• S: Accessible title on the copy to clipboard IDP metadata XML field

[kabel]

There is an added controller exposed to support the changed suggested in flipboxfactory/keychain#6