e2e

test(fdc): add e2e and unit tests to fdc #5391

Job	Run time
android (tests)	8m 17s
ios (tests)	30m 42s
android (packages/cloud_firestore/cloud_firestore/example)	8m 25s
ios (packages/cloud_firestore/cloud_firestore/example)	21m 12s
macos (tests)	9m 12s
macos (packages/cloud_firestore/cloud_firestore/example)	7m 10s
web (tests)	6m 24s
web (packages/cloud_firestore/cloud_firestore/example)	4m 31s
web-wasm (tests)	2m 55s
windows	7m 59s
web-wasm (packages/cloud_firestore/cloud_firestore/example)	15m 20s
windows-firestore	7m 17s
	2h 9m 24s

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