[ci] Add new flow GitHub action

[poteto]

Stack from ghstack (oldest at bottom):

• [ci] Remove circleci yarn_flags job #30030
• [ci] Add new flags GitHub action #30029
• [ci] Remove circleci yarn_flow job #30028
• [ci] Parallelize flow github action #30026
• -> [ci] Add new flow GitHub action #30025

Copies the existing circleci workflow for flow into GitHub actions. I
didn't remove the circleci job for now just to check for parity.

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
react-compiler-playground	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jun 21, 2024 3:04pm

[react-sizebot]

Comparing: 49a4887...41c6742

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.js	=	6.68 kB	6.68 kB	=	1.83 kB	1.83 kB
oss-stable/react-dom/cjs/react-dom-client.production.js	=	497.93 kB	497.93 kB	=	89.26 kB	89.26 kB
oss-experimental/react-dom/cjs/react-dom.production.js	=	6.69 kB	6.69 kB	=	1.83 kB	1.83 kB
oss-experimental/react-dom/cjs/react-dom-client.production.js	=	502.75 kB	502.75 kB	=	89.96 kB	89.96 kB
facebook-www/ReactDOM-prod.classic.js	=	597.17 kB	597.17 kB	=	105.33 kB	105.33 kB
facebook-www/ReactDOM-prod.modern.js	=	571.52 kB	571.52 kB	=	101.27 kB	101.27 kB
test_utils/ReactAllWarnings.js	Deleted	62.88 kB	0.00 kB	Deleted	15.69 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
test_utils/ReactAllWarnings.js	Deleted	62.88 kB	0.00 kB	Deleted	15.69 kB	0.00 kB

Generated by 🚫 dangerJS against 41c6742