Added conditional properties and required field assignment in uniforms-bridge-json-schema (closing #919).

[Monteth]

Fixed a bug where a field with no computed required subfields gets an empty 'required' prop. The same situation occurs with the 'properties'.

[codecov]

Codecov Report

Merging #936 (a767277) into master (6b1e3b2) will increase coverage by 0.03%.
The diff coverage is 95.45%.

❗ Current head a767277 differs from pull request most recent head c2a9f40. Consider uploading reports for the commit c2a9f40 to get more accurate results

@@            Coverage Diff             @@
##           master     #936      +/-   ##
==========================================
+ Coverage   97.45%   97.48%   +0.03%     
==========================================
  Files         202      202              
  Lines        3924     3938      +14     
  Branches      804      809       +5     
==========================================
+ Hits         3824     3839      +15     
  Misses         11       11              
+ Partials       89       88       -1     

Impacted Files	Coverage Δ
...niforms-bridge-json-schema/src/JSONSchemaBridge.ts	97.72% <90.00%> (+0.66%)	⬆️
packages/uniforms/src/joinName.ts	100.00% <100.00%> (ø)

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[radekmie]

Add tests, please.

[radekmie]

Also, let's add one more test with non-object field with anyOf that is required.