feat: make the variable map return early for noops

[BeksOmega]

The basics

• I branched from develop
• My pull request is against develop
• My code follows the style guide
• I ran npm run format and npm run lint

The details

Resolves

Fixes #6524

Proposed Changes

1. Makes it so that the variable map returns early in cases where renames are noops (other modificiations already did this correctly).
2. Moves firing create events from the VariableModel to the VariableMap.

Reason for Changes

1. This prevents us from getting into infinite event loops when sharing events between multiple workspaces. See here for an example/explanation.
2. This allows us to use variable models as backing data models without actually having them (e.g.) show up in the flyout.

Test Coverage

Added unit tests for creating, deleting, and renaming, and when they should fire events vs not fire events.

Documentation

N/A

Additional Information

This is not dependent on any parent branches, so it's ready for review!