Reduce circular dependencies

[quincylvania]

When building, a great deal of circular dependencies are listed. This is an annoyance more than anything, but we should make a point to reduce these in order to follow best practices.

[quincylvania]

So I was able to reduce the amount considerably.

• Importing from index files was by far the greatest issue since it would cause files to reference many unrelated files.
• I moved validationIssue and validationIssueFix to a separate file from core/validator
• I moved areaKeys and setAreaKeys to a separate file from core/context

The remaining circular dependencies seem legitimate and are generally import loops between modes, operations, and behaviors. I'm not sure how important it is to resolve these. For example:

Circular dependency: modules/modes/select.js -> modules/behavior/select.js -> modules/modes/select.js