[2.0] Atlas refactor

[dbirman]

Is your feature request related to a problem? Please describe.
We want "Atlas" as a concept to be agnostic to which atlas people are using, so that people outside AIND can use the data schema for their purposes. Atlas information should still get embedded in the metadata.

Describe the solution you'd like

• CCF is no longer a default, but an option
• AtlasSpace is some kind of metadata class, probably inherited from BrainGlobe
• AtlasTransform information is included, when available
• Insertions/SurgeryCoordinates reference the atlas space and reference coordinate. Maybe refactor to AtlasCoordinate and AtlasInsertion generic classes
• Upgraders in place for v1.x to 2.0

Additional context
Some additional discussion happening here:
https://alleninstitute.sharepoint.com/:w:/r/sites/NeuralDynamics/_layouts/15/Doc.aspx?sourcedoc=%7BE27B889D-27A1-4CC0-948C-10ADBE605654%7D&file=Data+Schema+2.0.docx&action=default&mobileredirect=true&DefaultItemOpen=1