Add partial support for format keyword

[OptimumCode]

This patch introduces:

• API for implementing user's format validator and registering it in the schema
• Support for data/time formats

Related to #54

[codecov]

Codecov Report

Attention: Patch coverage is 94.88636% with 9 lines in your changes are missing coverage. Please review.

Project coverage is 91.03%. Comparing base (b1bd666) to head (1356caf).

Files	Patch %	Lines
...son/schema/internal/formats/TimeFormatValidator.kt	70.00%	0 Missing and 6 partials ⚠️
...n/io/github/optimumcode/json/schema/Annotations.kt	0.00%	1 Missing ⚠️
...schema/internal/config/Draft7SchemaLoaderConfig.kt	75.00%	0 Missing and 1 partial ⚠️
...ternal/factories/general/FormatAssertionFactory.kt	97.50%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #72      +/-   ##
==========================================
+ Coverage   90.53%   91.03%   +0.49%     
==========================================
  Files          90       99       +9     
  Lines        2093     2252     +159     
  Branches      521      561      +40     
==========================================
+ Hits         1895     2050     +155     
+ Misses         40       36       -4     
- Partials      158      166       +8     

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