Implements raidRegistry client_type for Client

[codycooperross]

Purpose

Implements raidRegistry client_type for Client model.

closes: datacite/datacite#2114

Approach

• Adds raidRegistry to permissable client_types
• Adds a formatted title for aggregations

Open Questions and Pre-Merge TODOs

Learning

Types of changes

• Bug fix (non-breaking change which fixes an issue)

• New feature (non-breaking change which adds functionality)

• Breaking change (fix or feature that would cause existing functionality to change)

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