feat(spooler): Add EnvelopeStack based on SQLite #14692

Job	Run time
Test All Features (ubuntu-latest)	3m 38s
Test (macos-latest)	2m 24s
Test (windows-latest)	5m 55s
Setup build metadata	1s
Integration Tests	13m 24s
Test Python	1m 3s
Lint	3m 6s
Lint Rust Default Features	1m 37s
Build Relay Binary (relay, x86_64-unknown-linux-gnu)	7m 47s
Build Docker Image (relay)	31s
Sentry-Relay Integration Tests	11m 23s
Publish Relay to DockerHub	0s
Upload build artifacts to gocd	0s
self-hosted-end-to-end	13m 0s
Publish Relay to GCR	0s
	1h 3m 49s

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