feat: Implement msc 3381 polls #2004

# to view logs

Job	Run time
app_jobs / database_web_tests	41s
app_jobs / dart_web_compatible	54s
app_jobs / coverage_without_olm	2m 3s
app_jobs / coverage	2m 8s
app_jobs / e2ee_test (synapse)	1m 20s
app_jobs / pub-dev-dry-run	26s
app_jobs / e2ee_test (dendrite)	1m 57s
dart / dart_analyzer	35s
general / conventional_commits	3s
app_jobs / e2ee_test (conduit)	1m 46s
app_jobs / merge_converage	29s
app_jobs / review_app_coverage / deploy_review_app	7s
app_jobs / review_app_coverage / cleanup_review_app	10s
app_jobs / review_app_coverage / qa_app	0s
	12m 39s

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