Map project descriptor top-level (_) keys to OCI annotations

[jromero]

Based on a discussion with @samj1912 and previously inspired by buildpacks/pack#1049, I'd like to propose that we map the top-level (_) project descriptor keys to OCI annotations.

Mapping

[_]
schema-version = "<schema-version>"
id = "<string>"
name = "<string>" # → org.opencontainers.image.title
version = "<string>" # →  org.opencontainers.image.version
authors = ["<string>"] # →  org.opencontainers.image.authors
documentation-url = "<uri>" # →  org.opencontainers.image.documentation
source-url = "<uri>" # →  org.opencontainers.image. source

[[_.licenses]] # →  org.opencontainers.image.licenses
type = "<string>"
uri = "<uri>"

• Arrays could be mapped to comma separated values.

Questions

• What component would be responsible for this? platform, lifecycle, "prepare" phase?
• Should we map name → ...description so that we can map id → ...title?

[ttys3]

better add org.opencontainers.image.created too