chore: Add PR validation workflow #12602

Job	Run time
Ready-to-merge gate / Missing "ready-to-merge" label	3s
diff_check / diff_check	8s
detect-changes / Detect file changes	5s
Build legacy macos production no-frameworks	1s
Build new ios production no-frameworks	1s
Build new android dev no-frameworks	1m 37s
Build legacy ios dev dynamic-frameworks	1s
Build legacy android dev no-frameworks	1m 35s
Build legacy ios dev no-frameworks	1m 22s
Build legacy macos dev no-frameworks	1s
Build new ios dev no-frameworks	1s
Build legacy ios production dynamic-frameworks	1s
Build legacy android production no-frameworks	1m 36s
Build legacy ios production no-frameworks	1s
Build new android production no-frameworks	1m 36s
Test ${{ matrix.platform }} ${{ matrix.build-type }} REV2	1s
	8m 10s

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