Importable bloq manifest

[mpharrigan]

Another step forwards in having programmatic access to importing bloqs.

In an earlier PR we added the "bloq manifest", which is in bloqs/manifest.py and defines two static lists of strings (essentially). The first is a list of all the bloq class names (fully qualified). The bloq classes report their canonical import path with our _pkg_ class method, which defaults to one level up from the leaf module the class is defined in. This presumes that we "re-export" our classes one level up. This PR adds a check that the bloq class names from the manifest actually are importable and fixes the failures by re-exporting the import to an __init__.py or by overriding _pkg_ to make it a "local" bloq.

The test also compliments the "minimal install" test from #1871 by asserting that everything is at least importable without heavy dependencies except for specific subpackages (galois bloqs need the galois package is the main one)

[gemini-code-assist]

Code Review

This pull request makes galois an optional dependency by moving its imports to TYPE_CHECKING blocks and using string annotations. It exposes numerous bloq classes in package __init__.py files, updates the manifest list (BLOQ_CLASS_NAMES and BLOQ_EXAMPLE_OBJECTSTRINGS) to include and enable many previously commented-out bloq examples, and adds a new test (manifest_test.py) to ensure all manifest classes can be imported with minimal dependencies. Additionally, several classes now implement the _pkg_ classmethod to correctly resolve their package names. I have no feedback to provide as there are no review comments.