Support Draft 2020-12 and refactor schema retrieval

[justin-tay]

Closes #920, closes #884, closes #877, closes #855, closes #854, closes #840, closes #742

This PR includes breaking changes.

This adds support for the following required for Draft 2020-12 support

• $dynamicRef
• $dynamicAnchor
• $vocabulary

This refactors the schema retrieval codes as the ID is based on IRI and not URI.
Note that Java does not support IRIs. See https://cr.openjdk.org/%7Edfuchs/writeups/updating-uri/ for details.
The following are removed and replaced by SchemaLoader and SchemaMapper.

• URIFactory - No replacement. The resolve logic is in AbsoluteIRI.
• URISchemeFactory - No replacement as URIFactory isn't required anymore.
• URISchemeFetcher - No replacement. The SchemaLoaders are iterated and called.
• URITranslator - Replaced by SchemaMapper.
• URLFactory - No replacement as URIFactory isn't required anymore.
• URLFetcher - Replaced by UriSchemaLoader.
• URNURIFactory - No replacement as URIFactory isn't required anymore.

The SchemaLoader and SchemaMapper are configured in the JsonSchemaFactory.Builder.

As per the specification. The format keyword since Draft 2019-09 no longer generates assertions by default.
This can be changed by using a custom meta schema with the relevant $vocabulary or by setting the execution configuration to enable format assertions.

This PR also updates the documentation and includes a section on migrating to newer versions. This also includes miscellaneous fixes.

Functional Comparison

With Changes

Implementations	Overall	DRAFT_03	DRAFT_04	DRAFT_06	DRAFT_07	DRAFT_2019_09	DRAFT_2020_12
NetworkNt	pass: r:4694 (99.8%) o:2369 (100.0%) fail: r:9 (0.2%) o:1 (0.0%)		pass: r:600 (100.0%) o:251 (100.0%) fail: r:0 (0.0%) o:0 (0.0%)	pass: r:796 (100.0%) o:318 (100.0%) fail: r:0 (0.0%) o:0 (0.0%)	pass: r:880 (100.0%) o:541 (100.0%) fail: r:0 (0.0%) o:0 (0.0%)	pass: r:1198 (99.8%) o:625 (100.0%) fail: r:3 (0.2%) o:0 (0.0%)	pass: r:1220 (99.5%) o:634 (99.8%) fail: r:6 (0.5%) o:1 (0.2%)

Performance Comparison

With Changes

Benchmark	Mode	Score	Score Error (99.9%)	Unit
measureDraft_03_SchemaFriend	avgt	1.9071		ms/op
measureDraft_04_Everit	avgt	1.4849		ms/op
measureDraft_04_Justify	avgt	2.0652		ms/op
measureDraft_04_Medeia	avgt	1.7569		ms/op
measureDraft_04_NetworkNt	avgt	1.2460		ms/op
measureDraft_04_SchemaFriend	avgt	1.9748		ms/op
measureDraft_04_Vertx	avgt	2.8541		ms/op
measureDraft_06_Everit	avgt	1.4505		ms/op
measureDraft_06_Justify	avgt	1.8239		ms/op
measureDraft_06_Medeia	avgt	1.1763		ms/op
measureDraft_06_NetworkNt	avgt	1.0269		ms/op
measureDraft_06_SchemaFriend	avgt	2.7054		ms/op
measureDraft_06_Snow	avgt	11.193		ms/op
measureDraft_07_Everit	avgt	1.7233		ms/op
measureDraft_07_Justify	avgt	2.7318		ms/op
measureDraft_07_Medeia	avgt	1.6508		ms/op
measureDraft_07_NetworkNt	avgt	1.3515		ms/op
measureDraft_07_SchemaFriend	avgt	5.6883		ms/op
measureDraft_07_Snow	avgt	7.6221		ms/op
measureDraft_07_Vertx	avgt	3.8757		ms/op
measureDraft_2019_09_DevHarrel	avgt	6.1945		ms/op
measureDraft_2019_09_NetworkNt	avgt	2.3548		ms/op
measureDraft_2019_09_SchemaFriend	avgt	4.8612		ms/op
measureDraft_2019_09_Snow	avgt	19.639		ms/op
measureDraft_2019_09_Vertx	avgt	7.1400		ms/op
measureDraft_2020_12_DevHarrel	avgt	4.8767		ms/op
measureDraft_2020_12_NetworkNt	avgt	2.3653		ms/op
measureDraft_2020_12_SchemaFriend	avgt	4.2145		ms/op
measureDraft_2020_12_Skema	avgt	6.7389		ms/op
measureDraft_2020_12_Vertx	avgt	6.9798		ms/op

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 76.06516% with 191 lines in your changes missing coverage. Please review.

Project coverage is 79.04%. Comparing base (f3825f3) to head (90fdfd0).
Report is 98 commits behind head on master.

Files with missing lines	Patch %	Lines
src/main/java/com/networknt/schema/JsonSchema.java	72.48%	27 Missing and 14 partials ⚠️
...java/com/networknt/schema/DynamicRefValidator.java	62.79%	27 Missing and 5 partials ⚠️
...n/java/com/networknt/schema/JsonSchemaFactory.java	81.74%	9 Missing and 14 partials ⚠️
...a/com/networknt/schema/resource/SchemaLoaders.java	36.00%	16 Missing ⚠️
...com/networknt/schema/resource/UriSchemaLoader.java	46.42%	11 Missing and 4 partials ⚠️
...a/com/networknt/schema/resource/SchemaMappers.java	48.14%	14 Missing ⚠️
...com/networknt/schema/resource/MapSchemaLoader.java	0.00%	11 Missing ⚠️
...c/main/java/com/networknt/schema/RefValidator.java	84.31%	4 Missing and 4 partials ⚠️
...om/networknt/schema/ContentMediaTypeValidator.java	84.37%	3 Missing and 2 partials ⚠️
...networknt/schema/resource/DefaultSchemaLoader.java	84.61%	2 Missing and 2 partials ⚠️
... and 13 more

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Additional details and impacted files

@@             Coverage Diff              @@
##             master     #931      +/-   ##
============================================
+ Coverage     78.66%   79.04%   +0.37%     
- Complexity     1432     1504      +72     
============================================
  Files           136      143       +7     
  Lines          4692     4915     +223     
  Branches        896      932      +36     
============================================
+ Hits           3691     3885     +194     
- Misses          644      670      +26     
- Partials        357      360       +3     

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