Compliance with emmet-core 0.85.0

[esoteric-ephemera]

There are a significant number of structural changes to emmet-core in 0.85.0 that may impact workflows. Issues related to changes in the code structure and document models are amended here

Couple of notes:

• Some import strings will not be affected (e.g., emmet.core.tasks.TaskState) even though the actual python object has moved
• Other import strings, especially emmet.core.utils.ValueEnum --> emmet.core.types.enums.ValueEnum, will be affected
• Current solution allows for backwards compatibility for a time