Rename LocalAuthenticationOptions to LocalAuthentication

[Widcket]

⚠️ This PR contains breaking changes

• All new/changed/fixed functionality is covered by tests (or N/A)
• I have added documentation for all new/changed functionality (or N/A)

📋 Changes

This PR renames the LocalAuthenticationOptions class to just LocalAuthentication. This class is used as follows:

const options =
    LocalAuthenticationOptions(title: 'Please authenticate to continue');
final auth0 = Auth0('YOUR_AUTH0_DOMAIN', 'YOUR_AUTH0_CLIENT_ID',
    localAuthentication: options);
final credentials = await auth0.credentialsManager.credentials();

Setting it will enable the local authentication feature, which is disabled by default. So it's actually modeling the local authentication feature itself, instead of simply holding settings for a feature that is already in use. As such, it should be called just LocalAuthentication, without the Options suffix.

Compare it to the IdTokenValidationConfig class, which is used as follows:

const config = IdTokenValidationConfig(leeway: 10);
final credentials =
    await auth0.webAuthentication().login(idTokenValidationConfig: config);

The ID token validation feature is always enabled. This class merely allows to configure it, so it has Config as part of the class name, and also as part of the parameter name. It is not modeling the feature itself.

Config and Options have pretty much the same meaning in this context, yet are being used in classes that have different roles and achieve different results, which is inconsistent and might be confusing.