[PNE-6610] Expose more candidate attributes.

[anoto-moniz]

Expose the pinned metadata, hidden attribubte, and name of each candidate as read-only properties.

Citrine Python PR

Description

Please briefly explain the goal of the changes/this PR.
The reviewer should be able to understand why the change is being made by reading this description
and its links (e.g. JIRA tickets).

PR Type:

• Breaking change (fix or feature that would cause existing functionality to change)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Maintenance (non-breaking change to assist developers)

Adherence to team decisions

• I have added tests for 100% coverage
• I have written Numpy-style docstrings for every method and class.
• I have communicated the downstream consequences of the PR to others.
• I have bumped the version in __version__.py

[kroenlein]

Approving, though it'd be nice to see a FactoryBoy fixture being added for DesignCandidate in the context of adding new fields.