Feature: move database to modern .JSON format

[rkingsbury]

This PR is an extensive overhaul of the database system.

• replace Solute with a @dataclass based document model that houses all data associated with a particular species
• Consolidate all existing database data into a structured JSON file comprising serialized Solute classes. The source data and build process for this file have been removed from the repo (at least for now).
• Remove old Solute, ParamsDB, and Parameter classes
• Update Solution to pull data from the JSON file via maggma.Store.
• Add kwarg to Solution.__init__ to allow pointing to an arbitrary maggma.Store, not just the built-in one
• Add molar_volume data for 14 ions
• add maggma as a new dependency
• Linting

Documentation updates will be done later as part of another PR.