[formrecognizer] adjust TextAppearance to work with service changes

[kristapratico]

https://github.com/Azure/azure-rest-api-specs/blob/65f9a3d3cf22715604dc46a18ee5d88ec58bb413/specification/cognitiveservices/data-plane/FormRecognizer/preview/v2.1-preview.3/FormRecognizer.json#L2239-L2266

No longer have a Style type, properties for style/confidence are directly on the Appearance model.

Samples and tests will need update as well.

[kristapratico]

this swagger change was unintentional so this issue can be closed