[ABCA] Add UI Support for Configuring Trust in Client Attestations

[Awambeng]

Description

This is a proxy of:

• [ABCA] Add UI Support for Configuring Trust in Client Attestations keycloak/keycloak#44772

Add minimal admin UI support for configuring trust anchors for attestation.

This includes:

• Configure trusted attester issuers
• Configure attester JWKS per realm
• Validation (basic format checks) in UI
• Add descriptive help text for admin

estimated time: 2 days