Library theming: Update Modal component in design kit

[evwilkin]

Update the Modal component in the PatternFly design kit to align with the unified theme. Update Figma files, styles, documentation, and ensure unified visual consistency throughout.

Deliverables:

• Update tokens

• Include new variants

• Update branded icons

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Jira Issue: PF-3793

[evwilkin]

Closed via Jira sync - Jira issue PF-3793 was closed.

[evwilkin]

Closed via Jira sync - Jira issue PF-3793 was closed.

[patternfly-jira-sync]

Closed via Jira sync - Jira issue PF-3793 was closed.