Manifest: Gather libraries into an octez-libs library

Context

Depends on !8719 (merged)

Reduce the number of packages by gathering some octez libraries into a single package octez-libs with sub-libraries.

This merge request introduce the octez-libs package and add some libraries to it.

See docs/_build/api/odoc/_html/octez-libs/index.html for the list of octez-libs sub-libraries.

This is a preliminary work toward having a relevant set of opam packages. There will be follow-up MRs to complete octez-libs, and to gather other packages.

Manually testing the MR

• make -C manifest/
• make

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR