feat(spooler): Add EnvelopeStack based on SQLite #14652

Job	Run time
Lint Rust Default Features	1m 51s
Test (macos-latest)	2m 58s
Lint	2m 56s
Test (windows-latest)	7m 23s
Test All Features (ubuntu-latest)	4m 26s
Setup build metadata	1s
Integration Tests	13m 35s
Test Python	1m 30s
Build Relay Binary (relay, x86_64-unknown-linux-gnu)	8m 2s
Build Docker Image (relay)	43s
Sentry-Relay Integration Tests	11m 12s
Publish Relay to DockerHub	0s
self-hosted-end-to-end	13m 1s
Upload build artifacts to gocd	0s
Publish Relay to GCR	0s
	1h 7m 38s

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