[Blazor] API cleanups for the authentication Package

[javiercn]

• Add a couple of missing options to the OidcProviderOptions
• Remove string based APIs in favor of enums.

I didn't change RemoteAuthenticationActions to an enum for the following reasons:

• It is used as a parameter on the URL, and we don't want to tie the value used in the url to whether or not we can "cast to it". One option we can try here is to create a struct instead of an enum to represent it and have it hold the right value we can then use an implicit converter to cast to it, but I don't know if that will work.
• We still need to expose the string values of it, as they are part of the url, so we don't actually reduce the public API surface

[ghost]

Hello @pranavkm!

Because this pull request has the auto-merge label, I will be glad to assist with helping to merge this pull request once all check-in policies pass.

Do note that I've been instructed to only help merge pull requests of this repository that have been opened for at least 60 minutes, a condition that will be fulfilled in about 41 seconds. No worries though, I will be back when the time is right! 😉

p.s. you can customize the way I help with merging this pull request, such as holding this pull request until a specific person approves. Simply @mention me (@msftbot) and give me an instruction to get started! Learn more here.