Investigate UA String customization in generated code

[tjprescott]

The initializer for UserAgentPolicy in AzureCore looks like this:

    public convenience init(for clazz: AnyClass, telemetryOptions: TelemetryOptions) {
        let libraryBundleInfo = DeviceProviders.bundleInfo(for: clazz)
        let sdkName = libraryBundleInfo?.name ?? ""
        let sdkVersion = libraryBundleInfo?.version ?? ""
        self.init(sdkName: sdkName, sdkVersion: sdkVersion, telemetryOptions: telemetryOptions)
    }

We want to investigate whether anything in Swagger or the README could allow us to apply customizations in the generated code.