Make enableBigIntSupport a dynamic flag for Meta

[kassens]

Make enableBigIntSupport a dynamic flag for Meta

Should be an easy launch, but let's make this a dynamic flag to be safe.

[react-sizebot]

Comparing: b35be36...98ae796

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable/react-dom/cjs/react-dom.production.min.js	=	176.93 kB	176.93 kB	=	54.95 kB	54.95 kB
oss-experimental/react-dom/cjs/react-dom.production.min.js	=	173.36 kB	173.36 kB	=	54.08 kB	54.08 kB
facebook-www/ReactDOM-prod.classic.js	+0.11%	594.64 kB	595.27 kB	+0.07%	104.47 kB	104.55 kB
facebook-www/ReactDOM-prod.modern.js	+0.11%	577.90 kB	578.53 kB	+0.07%	101.50 kB	101.57 kB
test_utils/ReactAllWarnings.js	Deleted	65.49 kB	0.00 kB	Deleted	16.16 kB	0.00 kB

Significant size changes

Includes any change greater than 0.2%:

Expand to show

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
facebook-www/ReactServer-prod.modern.js	+0.76%	16.71 kB	16.84 kB	+0.80%	4.38 kB	4.41 kB
facebook-react-native/react/cjs/React-prod.js	+0.62%	20.40 kB	20.53 kB	+0.61%	5.12 kB	5.15 kB
facebook-www/React-prod.modern.js	+0.62%	20.47 kB	20.60 kB	+0.61%	5.12 kB	5.15 kB
facebook-react-native/react/cjs/React-profiling.js	+0.62%	20.55 kB	20.67 kB	+0.62%	5.13 kB	5.17 kB
facebook-www/React-prod.classic.js	+0.61%	20.76 kB	20.88 kB	+0.60%	5.19 kB	5.22 kB
facebook-www/React-profiling.modern.js	+0.61%	20.90 kB	21.03 kB	+0.60%	5.20 kB	5.23 kB
facebook-www/React-profiling.classic.js	+0.60%	21.19 kB	21.32 kB	+0.61%	5.27 kB	5.30 kB
test_utils/ReactAllWarnings.js	Deleted	65.49 kB	0.00 kB	Deleted	16.16 kB	0.00 kB

Generated by 🚫 dangerJS against 98ae796