Inherited Form Fields

### Description

I have form fields that are reused across multiple forms. I want to put them into a base class and have the individual forms inherit some of their fields from their parent class.

### Steps to Reproduce

Simplified example: 

public class GeneralSettings implements Serializable {

    @Tab(title = "General Settings", index = 0)
    @CheckBox(title = "Enabled")
    private boolean enabled;

    public boolean getEnabled() {
        return enabled;
    }
}

public class MoreSettings extends GeneralSettings {

    @Tab(title = "More Settings", index = 1)
    private int maximum;

    public int getMaximum() {
        return maximum;
    }
}

To run:
UiForm uiForm = UiFormSchemaGenerator.get().generate(MoreSettings.class);

**Expected behavior:** [What you expect to happen]

I expect the schema to contain two properties and the form to contain two nodes: enabled and maximum

**Actual behavior:** [What actually happens]

The generated schema contains both fields, but the form contains only the field declared in MoreSettings, not the field declared in its parent.

### Versions

1.0.0

### Additional Information

I see a call to getDeclaredFields() inside UiFormSchemaGenerator.generate() so maybe this behavior is intentional. Please let me know.

Thanks!
