feature: implement toHaveAccessibleValue Jest matcher

[mdjastrzebski]

Describe the Feature

toHaveAccessibleName is a Jest DOM matcher asserting that given element has certain accessible name: text content or a11y label.

RNTL already contains some code working with accessible name, namely *ByRole query accepts an optional name param. This matcher should compare expect name parameter with all of these:

1. text content of element referenced by accessibilityLabelledBy / aria-labelledby prop
2. accessbilityLabel / aria-label prop
3. text content of given element

These should be evaluated in that particular order.

Possible Implementations

Proposed API:

export function toHaveAccessibleName(
  this: jest.MatcherContext,
  element: ReactTestInstance,
  expectedName?: TextMatch,
) 

The matcher should:

1. Validate that it is invoked on a host element
2. When expectedName param is provided check if it matches element's accessible name
3. When expectedName is not provided check if element has accessible name

Each matcher should have a fairly comprehensive test suite.

Related Issues

#1454

[tarunrajput]

@mdjastrzebski, I'd like to implement this

[mdjastrzebski]

@tarunrajput go ahead, it's yours now!

[mdjastrzebski]

Resolved in #1496!

[mdjastrzebski]

🎉 Release in version: v12.4.0