fix(resolver): don't attach $$ref meta patches to $ref origin locations

[shockey]

Description

$$ref meta patches were being attached to the path referenced by a $ref as well as the destination, which was caused by the JSON Patch processor linking the $ref source and destination by referencing the same in-memory Object in both positions. This is bad for two reasons:

1. there's no need for information about the $ref source path, as it can be deduced by the data's back itself
2. it becomes impossible to consume $$refs as a marker of a $ref previously being in that position

This PR eliminates this issue by breaking the Object reference between the source and destination.

It also:

• moves to fast-json-patch@1.2
• refactors use of op: '_get' to fast-json-patch's new getValueByPointer interface

Motivation and Context

• Unblocks No validation errors if local references are misspelled as '#definitions/...' swagger-editor#1560.
• Paves the way for our lazy resolver implementation.

How Has This Been Tested?

I updated a handful of unit tests to match the new $$ref implementation.

Types of changes

• No code changes (changes to documentation, CI, metadata, etc)
• Dependency changes (any modification to dependencies in package.json)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Breaking internal API change (requires minor version bump).

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.