Feature: Support flexible priority in solve task

[jpcorreia99]

Checklist

• [x] I added a descriptive title
• [x] I searched open requests and couldn't find a duplicate

What is the idea?

Following https://github.com/conda/rattler/pull/598, it would be very useful if rattler/resolvo also supported flexible priority: With flexible channel priority, the solver may reach into lower priority channels to fulfill dependencies, rather than raising an unsatisfiable error

Why is this needed?

The main use case I see for this is user requesting for a package A==2.0.0 and getting an error because this newer version of the package is not present in the first priority channel.

What should happen?

Frankly, I'm not sure I have enough knowledge of the internals to be very opinionated here. But I'd like to see A==2.0.0 be satisfied if possible, given the users acknowledgement that they're searching for a specific version

Additional Context

No response

[baszalmstra]

Thats for the feature request. I am not entirely sure how to implement this yet.

@wolfv would sorting the packages by channel priority work?