Clean up thc_notebook_utils and use qualtran exclusively in chemistry code.

[fdmalone]

From #350:

1. Migrate all code to using the qualtran codebase (no cirq_ft). Currently only using qroam as there are still some repr issues using the qualtran SelectSwapQROM when visualizing bloq counts.
2. Strip out some useful generalizers.
3. Think about better way to group / classify bloqs which can be useful for costing. Maybe a bloq.group_counts_by_type(classifier_callable) and bloq.get_subtree_bloq_counts(parent_of_subtree?). I imagine the second way is already possible to do.