Migrated `connectField` tests to @testing-library/react

[piotrpospiech]

Is part of https://github.com/vazco/uniforms/issues/1130

• added connectField RTL tests
• removed enzyme connectField tests

Main changes compare to enzyme tests:

• removed from when rendered with label test following labelVariants:

  
  const labelA = <span style={{ color: 'red' }}>Error</span>;
  const labelB = <span style={{ color: 'green' }}>OK</span>;

['Props', labelB, 'Props'], ['', labelB, ''], [labelA, '', labelA], [labelA, 'Schema', labelA], [labelA, labelB, labelA], [labelA, undefined, labelA], [undefined, labelB, labelB],

- changed in the `is able to set another field value` test, tested value from `object` to `string` to have the same type in those two fields

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (1a6ca83) 94.66% compared to head (02d0e22) 94.66%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1301 +/- ## ======================================= Coverage 94.66% 94.66% ======================================= Files 231 231 Lines 3821 3821 Branches 1029 1029 ======================================= Hits 3617 3617 Misses 82 82 Partials 122 122 ```

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