Add back all_rulesets in favor of rulesets property cleverness

[collindutter]

• I have read and agree to the contributing guidelines.

Problem:

RuleMixin._rulesets is marked as serializable, but it has an alias, rulesets. When serializing RuleMixin the property ,rulesets, gets serialized rather than the field.

This leads to some unintended behavior where the serialized rulesets field contains the "Default Ruleset" added by the ruleset property.

Solution:

Remove the cleverness of having rulesets be both a field and property by re-introducing all_rulesets. all_rulesets is only used at runtime and is not serialized.

Issue ticket number and link

Closes #1465

[collindutter]

I think this is breaking enough to hold off until 2.0, but what do reviewers think?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

📢 Thoughts on this report? Let us know!