Add ServiceProvider aware overloads to Configure

[fredrikhr]

Provides overloads to the Configure methods that do not require an actual IConfiguration instance, but accept a delegate that enables IConfiguration to be retrieved from the IServiceProvider when IOptions<TOptions> is requested.

However, this requires IConfiguration to be registered in the service container.

[fredrikhr]

Alternatively, the configAccessor argument could be changed to a Func<IServiceProvider, IConfiguration> delegate instead. This might give people a better idea of what this overload is for, as it would line up with the AddSingleton (and related) extension methods.

[HaoK]

This should no longer be needed, you should be able to do something similar via the new Configure overload that hangs off OptionsBuilder that accepts generic dependencies,

see edc21af