Make long lists of demographic unknowns collapsible

[macfarlandian]

Description of the change

Particularly with time series data, our treatment of people with unknown demographic properties can get pretty unwieldy if there are lots of them. We never had this problem in ND and so we never solved for it, but it does appear in the PA parole data. This just clamps the list at 3 entries with a button to expand or collapse it in place as needed. (With 3 or fewer entries the button will not be shown.)

The height change is animated with a technique I've used in several other places. Rather than duplicate it yet another time I have refactored it into a wrapper component. I haven't seen any regression in those sections. (This does make the PR look bigger than it really is due to indentation changes; you might want to hide them while reviewing.)

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Configuration change (adjusts configuration to achieve some end related to functionality, development, performance, or security)

Related issues

Closes #439

Checklists

Development

These boxes should be checked by the submitter prior to merging:

• Manual testing against realistic data has been performed locally

Code review

These boxes should be checked by reviewers prior to merging:

• This pull request has a descriptive title and information useful to a reviewer
• This pull request has been moved out of a Draft state, has no "Work In Progress" label, and has assigned reviewers
• Potential security implications or infrastructural changes have been considered, if relevant

[coveralls]

Pull Request Test Coverage Report for Build 908048887

• 34 of 35 (97.14%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.1%) to 85.133%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
spotlight-client/src/VizDemographicsByCategory/VizDemographicsByCategory.tsx	1	2	50.0%

Totals
Change from base Build 907448618:	0.1%
Covered Lines:	1936
Relevant Lines:	2151

---

💛 - Coveralls