[Csharp] Bugfix: Updated all C# templates ToJson method not to conflict reference withmodel properties

[Havunen]

This PR fixes an issue where model contains property called "Formatting" or "JsonConvert" build fails to conflicting reference.
I tested opening generated sample projects in Visual Studio 2019 and compiled them.

The error being fixed:

Error CS1061	'Model' does not contain a definition for 'Indented' and no accessible extension method 'Indented' accepting a first argument of type 'Model' could be found (are you missing a using directive or an assembly reference?)

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[Havunen]

@mandrean @frankyjuang @shibayan Please review, it seems I cannot assign for review, option is grayed out in Github

[Havunen]

I dont understand how this circle ci failure is related to my change.

[ERROR] Plugin org.springframework.boot:spring-boot-maven-plugin:2.2.9.RELEASE or one of its dependencies could not be resolved: Failed to read artifact descriptor for org.springframework.boot:spring-boot-maven-plugin:jar:2.2.9.RELEASE: Could not transfer artifact org.springframework.boot:spring-boot-maven-plugin:pom:2.2.9.RELEASE from/to central (https://repo.maven.apache.org/maven2): Connection reset -> [Help 1]

@wing328

[wing328]

Pushed 816be37 to update the samples.

[wing328]

LGTM