Share the same Animated.Value amongst transitions that happen in the same commit

[martinbooth]

Right now, updating state which affects transitioning properties accross multiple components results in each component creating its own Animated.Value and starting the animation in an effect.

This results in animations that are not in sync as they should be.

In this PR, transitions with the same delay, duration, timing function share the same Animated.Value as long as they're part of the same commit.

useLayoutEffect is used to either create the Animated.Value or find an existing suitable one to use.

Since all layout effects run before effects, we can assume that by the time any component's effect runs, all Animated.Values have been created or shared.

One of the component's effects will then kick off the animation and empty the shared animation config map so that future commits don't reuse any of the Animated.Values that were created. The other component's effects will be no-ops.

Finally, reference counting is used to ensure only the last component that unmounts would stop the animation if it was still running since now they are shared it would be disruptive to stop the animation unless the component was the last one relying on it

[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/dom/index.js
· compressed	2,513	2,513	1.00
· minified	8,695	8,695	1.00
react-strict-dom/dist/dom/runtime.js
· compressed	855	855	1.00
· minified	2,435	2,435	1.00
react-strict-dom/dist/native/index.js
· compressed	16,243	16,372	1.01	+
· minified	60,801	61,245	1.01	+

[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	1,139,622	1,141,513	1.00	+
· small with units	407,192	421,523	1.04	+
· small with variables	648,206	656,008	1.01	+
· several small	310,173	317,082	1.02	+
· large	205,304	203,110	0.99	-
· large with polyfills	142,007	141,401	1.00	-
· complex	96,868	98,124	1.01	+
· unsupported	214,433	215,549	1.01	+
css.createTheme
· simple theme	223,048	226,657	1.02	+
· polyfill theme	213,354	212,613	1.00	-
css.props
· small	242,433	244,944	1.01	+
· small with units	191,212	191,087	1.00	-
· small with variables	106,126	106,369	1.00	+
· small with variables of units	74,015	74,973	1.01	+
· large	103,970	104,496	1.01	+
· large with polyfills	36,921	37,102	1.00	+
· complex	23,405	23,048	0.98	-
· unsupported	146,180	145,417	0.99	-
· simple merge	162,779	161,982	1.00	-
· wide merge	17,701	17,572	0.99	-
· deep merge	17,385	17,195	0.99	-
· themed merge	31,385	31,241	1.00	-