Component dependencies feature

[itowlson]

In Spin 3, we can satisfy components' imported interfaces by wiring them up in the manifest. The v3 docs will need to cover this. We should consider:

• Reference documentation
• Concepts documentation (probably fits into the "writing apps" and/or "building apps" section, or might need a new unit about components as a concept, component registries, etc.)
• Any caveats around Cloud / SpinKube / registries / etc.
• Tutorial / example
  • We could have some pre-built demo components and WITs for this in the Fermyon registry (although I am not sure what tooling can use OCI registries right now)

[fibonacci1729]

I agree re: adding components as a concept and component registries would be really useful given that source and dependencies both reference "registry" as a concept; however, I'm partial to including that as a followup action item.