Update reCAPTCHA v3 to not use obsolete GetSetting method

[bjarnef]

Currently in Umbraco Forms v8.7.1 it seems the Fieldtype.Recaptcha3.cshtml is using the obsolete method to get a setting:

var siteKey = Umbraco.Forms.Core.Configuration.GetSetting("RecaptchaV3SiteKey");

Before reCAPTCHA v3 was added to Umbraco Forms in v8.7 I had this in a custom reCAPTCHA v3 field:

var configuration = Current.Factory.GetInstance<Umbraco.Forms.Core.IFacadeConfiguration>();
var siteKey = configuration.GetSetting("RecaptchaPublicKey");

It would be great to use this to not use the obsolete method.

[AndyButland]

What you have is better @bjarnef I agree, but although obsolete, this other method won't be removed in a V8 release. And for V9, we have had to change configuration access anyway (to use IOptions and appSettings,json. So I don't think we need to be too concerned about this.

[bjarnef]

Agree we don't need to remove the method as it would be a breaking change and developer may use the obsolete GetSetting() method in custom fields.
However I guess it should be fine to update the Fieldtype.Recaptcha3.cshtml included in Umbraco Forms to use the new way to fetch a setting? The GetSetting was obsolete before Umbraco 8.7, but not sure since which version is has been marked as obsolete.