feat(dfx-orbit): Introduce `upload_and_propose` function to `ic-assets`

[Sawchord]

Description

This PR adds a upload_and_propose function to the ic-assets lib. This functionality would be needed by the dfx-orbit tool to work correctly.

The function works similar to upload, however it calls propose_commit_batch instead of commit_batch and returns the batch ID.

How Has This Been Tested?

Unit tests still pass.

Open issues:

The dfx-orbit tool needs some functions that previously have been private. Right now, I simply set the corresponding modules pub. It could also make sense to re-export the necessary functionality to some module to have it all in one place.

Checklist:

• [x] The title of this PR complies with Conventional Commits.
• [ ] I have edited the CHANGELOG accordingly.
• [ ] I have made corresponding changes to the documentation.