Support custom JsonSerializerOptions. (#7272) (#7289)

* Add Visual Studio spell checker configuration

* Generate converters as partial classes

* Rename SourceSerialization helper

* Prefer throw helper for missing settings

* Support custom JsonSerializerOptions

* Cleanup docs and add initial custom serialization docs

* Tweak formatting of code for docs

* Adding "Configuring custom `JsonSerializerOptions`" section

* Adding "Registering custom `System.Text.Json` converters"

* Add XML doc comments for public methods on serializer types

* Add Creating a custom Serializer section

* Finalise documentation for serialization

Co-authored-by: Steve Gordon <[email protected]>

Author: github-actions[bot]

.editorconfig

@@ -200,6 +200,9 @@ resharper_csharp_accessor_owner_body=expression_body
 resharper_redundant_case_label_highlighting=do_not_show
 resharper_redundant_argument_default_value_highlighting=do_not_show
 
+spelling_languages=en-us,en-gb
+spelling_exclusion_path=.\exclusion.dic
+
 [Jenkinsfile]
 indent_style = space
 indent_size = 2