feat(spooler): Add EnvelopeStack based on SQLite #14650

Job	Run time
Lint	1m 53s
Lint Rust Default Features	1m 48s
Test (macos-latest)	1m 58s
Test (windows-latest)	1m 39s
Test All Features (ubuntu-latest)	1m 53s
Test Python	1m 12s
Setup build metadata	1s
Integration Tests	1m 53s
Build Relay Binary (relay, x86_64-unknown-linux-gnu)	1m 45s
Build Docker Image	1s
Publish Relay to DockerHub	1s
Publish Relay to GCR	1s
Upload build artifacts to gocd	1s
Sentry-Relay Integration Tests	1s
self-hosted-end-to-end	1s
	14m 8s

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