feat(spooler): Add EnvelopeStack based on SQLite #14644

Job	Run time
Lint	3m 2s
Lint Rust Default Features	1m 20s
Test (macos-latest)	2m 15s
Test (windows-latest)	5m 59s
Setup build metadata	1s
Test All Features (ubuntu-latest)	3m 40s
Test Python	50s
Integration Tests	6m 17s
Build Relay Binary (relay, x86_64-unknown-linux-gnu)	6m 5s
Build Docker Image	1s
Publish Relay to DockerHub	1s
Sentry-Relay Integration Tests	1s
self-hosted-end-to-end	1s
Publish Relay to GCR	1s
Upload build artifacts to gocd	1s
	29m 35s

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