Used specPath for isShownKey and some cleanup to support

[geraldglynn]

Description

The isShownKey in Models does not always reflect its position in Definition YAML.
Currently the isShownKey base is still ['models'] in some places e.g. in readyToScroll()
This update keeps it consistent when used in readyToScroll(), isShown(), show(), requestResolvedSubtree(), etc.
– ['definitions'] for Swagger 2.0
– ['components', 'schemas'] for OAS3
When possible Im.List is used aka specPath; when an Im.List is not possible the array version fullPath is used.

Motivation and Context

– The isShownKey is used in show() which displays in the URL fragment hash
– Currently there is an issue with toggling an individual Model
– Inconsistencies in how isShownKey is built has caused confusion

How Has This Been Tested?

– This has been manually tested on local development

Screenshots (if appropriate):

Checklist

My PR contains...

• No code changes (src/ is unmodified: changes to documentation, CI, metadata, etc.)
• Dependency changes (any modification to dependencies in package.json)
• Bug fixes (non-breaking change which fixes an issue)
• [ x] Improvements (misc. changes to existing features)
• Features (non-breaking change which adds functionality)

My changes...

• are breaking changes to a public API (config options, System API, major UI change, etc).
• are breaking changes to a private API (Redux, component props, utility functions, etc.).
• are breaking changes to a developer API (npm script behavior changes, new dev system dependencies, etc).
• are not breaking changes.

Documentation

• My changes do not require a change to the project documentation.
• My changes require a change to the project documentation.
• If yes to above: I have updated the documentation accordingly.

Automated tests

• My changes can not or do not need to be tested.
• My changes can and should be tested by unit and/or integration tests.
• If yes to above: I have added tests to cover my changes.
• If yes to above: I have taken care to cover edge cases in my tests.
• All new and existing tests passed.

[tim-lai]

@geraldglynn This PR is breaking. I also tried updating to latest branch, still breaking. It also needs Cypress tests to confirm that the models display, expand, collapse. Thanks!