[Bug] Remove the weird pattern for newing up redundant copies of MicrosoftIdentityOptions

[jmprieur]

**Which Version of Microsoft Identity Web are you using ?
Microsoft Identity Web 0.1.5-preview

Where is the issue?

• Web App
  • [x ] Sign-in users
  • [ x] Sign-in users and call web APIs
• Web API
  • [x ] Protected web APIs
  • [x ] Protected web APIs call downstream web APIs

Other? - please describe;

Repro

Remove the weird pattern for newing up redundant copies of MicrosoftIdentityOptions
WebApiAuthenticationBuilderExtensions.cs#L85-L88
WebAppAuthenticationBuilderExtensions.cs#L74-L75
WebApiCallsWebApiAuthenticationBuilderExtensions.cs#L63-L66
WebAppCallsWebApiAuthenticationBuilderExtensions.cs#L101-L102

Expected behavior

• Injecting something IOptions from the container (in 5.0)
• In 3.1. @chris will provide an ugly work around.

See also #234 which leverages the same mechanism

Proposed design

• in https://github.com/AzureAD/microsoft-identity-web/blob/master/src/Microsoft.Identity.Web/WebApiAuthenticationBuilderExtensions.cs#L83, we already have a service provider.

1. Use it to get a required service of IOptions.

MicrosoftIdentityOptions microsoftIdentityOptions = serviceProvider.GetRequiredService<IOptions<MicrosoftIdentityOptions>>().Value;

2. Note that it's not needed to call configureMicrosoftIdentityOptions(microsoftIdentityOptions); because it's called automatically as registered by : https://github.com/AzureAD/microsoft-identity-web/blob/master/src/Microsoft.Identity.Web/WebApiAuthenticationBuilderExtensions.cs#L72

• same thing for https://github.com/AzureAD/microsoft-identity-web/blob/master/src/Microsoft.Identity.Web/WebAppAuthenticationBuilderExtensions.cs#L110, but the lines involving the MicrosoftIdentityOptions should be moved inside the builder.AddOpenIdConnect callback. The code could be something like:

    builder.Services.TryAddEnumerable(ServiceDescriptor.Singleton<IValidateOptions<MicrosoftIdentityOptions>, MicrosoftIdentityOptionsValidation>());
  
  #if DOTNET_CORE_31
            builder.AddOpenIdConnect(openIdConnectScheme, options =>
            {
                // TODO: replace by the work around that @Tratcher will provider
                IServiceProvider serviceProvider = builder.Services.BuildServiceProvider();
  #else
            builder.AddOpenIdConnect<IServiceProvider>(openIdConnectScheme, (options, serviceProvider) =>
            {
  #endif
                MicrosoftIdentityOptions microsoftIdentityOptions = serviceProvider.GetRequiredService<IOptions<MicrosoftIdentityOptions>>().Value;

• in https://github.com/AzureAD/microsoft-identity-web/blob/master/src/Microsoft.Identity.Web/WebApiCallsWebApiAuthenticationBuilderExtensions.cs#L78 and https://github.com/AzureAD/microsoft-identity-web/blob/master/src/Microsoft.Identity.Web/WebAppCallsWebApiAuthenticationBuilderExtensions.cs#L124, do something similar as in the previous 2 files.

[jennyf19]

Included in 0.2.0-preview release