feat: Add group name resolution for DataZone memberships

[kompasbank-lasse]

Enables specifying Identity Center group names directly in project owner/contributor lists for DataZone domains.

Changes

• Add get_group_id_by_name() function with pagination support
• Enhance manage_project_memberships() with username → group name fallback logic

Usage

project:
  owners: 
    - "john.doe@mail.com"                    # username
    - "arn:aws:iam::123:role/MyRole"         # IAM role ARN
    - "MyGroupName"                          # Identity Center group name (new)


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[kompasbank-lasse]

@abaror75 @vasu2856