Cuelang support for Updatecli manifest

[olblak]

The purpose of this discussion is to gather feedback on the Cuelang support in Updatecli.

[olblak]

Recently interesting discussion happened in #5352
So far we have a few additional topics to clarify

Cuelang Module:

Would it be better to leverage Cuelang module instead of working in an isolation scope with external libraries, etc.
It would allows us to leverage standard libraries, import, etc.
This may also require additional work on the OCI policies to be able to publish Cuelang policies.

Dynamic values

It's quite common to reuse source output using the syntax {{ source "sourceID" }} maybe it can be interesting to have a something using Cuelang approach instead of the Cuelang syntax.