feat: add .toBeJsonMatching(expectation) matcher

[Belema]

I have closed PR #481 by accident, so here it is again.

---

What

This adds support for a new custom matcher .toBeJsonMatching(...).

Why

This matcher is useful when one wants to check that a function has been called with a JSON string that satisfies some constraints,

expect(fn).toHaveBeenCalledWith(
  expect.toBeJsonMatching({ key1: 'value1' })
);

Housekeeping

• Unit tests
• Documentation is up to date
• No additional lint warnings
• Typescript definitions are added/updated where relevant

[changeset-bot]

🦋 Changeset detected

Latest commit: ffa55b5

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
jest-extended	Minor

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