Add advise to CNBi pipelines

[codificat]

From the CNBi feature description:

6. The system must provide users some capability to check dependencies and verify any dependency issues as they are defining the components in a notebook or a new custom image.

   P1: When users create custom NB images, the system should perform some automatic check for dependencies, security issues, and compatibility across components included in the image. The system should present a message with any issues found, but should not prevent users from proceeding.
   P2: The system should provide users an option to check for dependencies, security issues, and compatibility across components prior to attempting to create a custom NB image. This should be an optional tool accessible from the UI. The use case is enabling users to check for issues in a notebook/image prior to the process of trying to create a custom image.
   P2: The system should provide optional guidance to identify dependencies (eg specific package versions needed) at the point of installing packages. For example, a user could add a TensorFlow version in a notebook and the user could access a tool to get recommendations on other package versions to install. Additionally, if a user installs an incompatible version of dependency (eg. the wrong version of scipy to work with the added version of TensorFlow), the user could access a UI option to identify issues and make corrections.

Notes:

This should be an optional tool that is available prior to creating a custom NB image. This could be at the point of installation or after I've installed several components & I want to check the versions & compatibility.

[codificat]

Notes from the backlog grooming session.

About the user experience: we must keep in mind that getting advice from Thoth can be a relatively slow process. Any action involving Thoth advice would not be interactive in the web UI.

Other Thoth API interactions that do not involve advise can be interactive, e.g. to validate or obtain a list of valid/known package versions.

This should be an optional tool that is available prior to creating a custom NB image.

All of this basically implies that Thoth advice and/or any sort of guided dependency check/resolution should have its own, separate pipeline - and a mechanism to trigger it without triggering an image build pipeline.

Also, we will prioritize the build workflows first and work on this afterwards.

/kind feature
/priority important-longterm