Reorganize unit and benchmark tests

[necolas]

The goal of these changes is to make it easier to navigate and update unit tests, while reducing the reliance on implementation details (and test-only abstractions) in tests

Refactor unit tests

• Break up large test files into smaller test files for each API
• Do not use 'css.props' (implementation detail) in unit tests

Remove css.props benchmark

• It doesn't run on Hermes, so is only a proxy for React Native perf
• It has been replaced by e2e React Native tests (Fantom) internally
• The API itself doesn't exist on web and the plan is to remove it from native

[github-actions]

workflow: benchmarks/size

Comparison of minified (terser) and compressed (brotli) size results, measured in bytes. Smaller is better.

Results	Base	Patch	Ratio
react-strict-dom/dist/web/index.js
· compressed	3,251	3,251	1.00
· minified	10,375	10,375	1.00
react-strict-dom/dist/web/runtime.js
· compressed	1,645	1,645	1.00
· minified	4,131	4,131	1.00
react-strict-dom/dist/native/index.js
· compressed	16,232	16,232	1.00
· minified	62,962	62,962	1.00

[github-actions]

workflow: benchmarks/perf (native)

Comparison of performance test results, measured in operations per second. Larger is better.

Results	Base	Patch	Ratio
css.create
· small	1,136,369	1,144,670	1.01	+
· small with units	495,175	496,230	1.00	+
· small with variables	671,829	675,372	1.01	+
· several small	353,169	351,396	0.99	-
· large	199,540	200,686	1.01	+
· large with polyfills	146,997	149,132	1.01	+
· complex	102,779	103,451	1.01	+
· unsupported	210,392	210,451	1.00	+
css.createTheme
· simple theme	226,362	225,035	0.99	-
· polyfill theme	213,907	213,661	1.00	-
css.props
· small	229,178
· small with units	185,823
· small with variables	111,628
· small with variables of units	82,493
· large	96,342
· large with polyfills	38,122
· complex	21,871
· unsupported	138,476
· simple merge	159,253
· wide merge	16,800
· deep merge	16,683
· themed merge	32,195