feat(spooler): Add EnvelopeStack based on SQLite #14645

Job	Run time
Lint Rust Default Features	1m 18s
Test (macos-latest)	2m 20s
Test (windows-latest)	8m 26s
Lint	2m 43s
Test All Features (ubuntu-latest)	4m 43s
Test Python	57s
Setup build metadata	1s
Integration Tests	11m 27s
Build Relay Binary (relay, x86_64-unknown-linux-gnu)	8m 35s
Build Docker Image (relay)	30s
Sentry-Relay Integration Tests	10m 32s
Publish Relay to DockerHub	0s
self-hosted-end-to-end	13m 14s
Upload build artifacts to gocd	0s
Publish Relay to GCR	0s
	1h 4m 46s

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