[C#] Fix invalid implicit casts

[devhl-labs]

Fixes #21476

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---

Summary by cubic

Fixes invalid implicit casts in generated C# generichost models by returning the underlying value from Option<T> getters, eliminating compile-time errors in optional and enum properties.

• Bug Fixes
  • Updated modelGeneric.mustache so getters use .Value on Option<T> fields instead of returning the Option itself.
  • Regenerated C# samples across net4.7, net4.8, net8, and net10 to apply the fix in enums, AnyOf, and other models.
  • No breaking API changes; property types and serialization remain the same.

^{Written for commit 82f1dae. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 182 files

Note: This PR contains a large number of files. cubic only reviews up to 75 files per PR, so some files may not have been reviewed.

[metoule]

You didn't make the change on this line (L243), was this on purpose, or just something that was missed?

Suggested change

public {{{datatypeWithEnum}}}{{#lambda.first}}{{#isNullable}}{{>NullConditionalProperty}} {{/isNullable}}{{^required}}{{nrt?}}{{^nrt}}{{#vendorExtensions.x-is-value-type}}?{{/vendorExtensions.x-is-value-type}}{{/nrt}} {{/required}}{{/lambda.first}} {{name}} {{#required}}{ get; {{^isReadOnly}}set; {{/isReadOnly}}}{{/required}}{{^required}}{ get { return this.{{name}}Option.Value; } {{^isReadOnly}}set { this.{{name}}Option = new{{^net70OrLater}} Option<{{{datatypeWithEnum}}}{{>NullConditionalProperty}}>{{/net70OrLater}}(value); } {{/isReadOnly}}}{{/required}}

[devhl-labs]

Please consider sending PRs #23344