SDK-2816: Support Digital IDs in IDV

[mehmet-yoti]

Summary

Adds Digital ID support to the IDV/DocScan session flow in the PHP SDK (yoti-php-sdk):

• Relying Businesses can enable digital IDs and restrict them to specific providers when creating a session (both DOCUMENT_RESTRICTIONS and ORTHOGONAL_RESTRICTIONS filters, and anywhere else a DocumentFilter is already reused, e.g. id_verse's issuing-authority sub-check).
• Relying Businesses can fetch the list of digital ID shares performed in a session, including any per-share error.
• The digital ID provider is now exposed on ID_DOCUMENT resources when the document came from a digital ID share.
• The session configuration fetch now exposes which providers are supported per document type.

No value validation was added for provider names or allow_digital_ids — per the ticket, that's left to the backend.