feat: Add `STACK` and `DEMO` templating parameters #454

Job	Run time
General Pull Request Checks / Run Cargo Tests	1m 22s
General Pull Request Checks / Run Cargo Udeps	2m 38s
General Pull Request Checks / Run Cargo Deny (advisories)	51s
General Pull Request Checks / Run Cargo Deny (bans licenses sources)	52s
General Pull Request Checks / Run RustDoc	7m 15s
General Pull Request Checks / All tests passed	2s
Helm Chart Check	21s
Publish arm64 Image	13m 31s
Publish amd64 Image	14m 13s
Build and publish manifest list	41s
	41m 46s

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