Extend AuthCodeMSALBrowserAuthenticationProvider to support for multi-tenancy.

[SimonSimCity]

Is your feature request related to a problem? Please describe the problem.

On my multi-tenancy application, I cannot see an option how I can get a token for a user for a specific tenant. The provider AuthCodeMSALBrowserAuthenticationProvider always provides the MSGraph instance with the token of the home tenant of the user.

Describe the solution you'd like.

When instantiating AuthCodeMSALBrowserAuthenticationProvider, allow user user to pass in the authority of the token he wants to use.

Additional context?

• https://github.com/AzureAD/microsoft-authentication-library-for-js/blob/dev/lib/msal-common/docs/multi-tenant-accounts.md#authenticating-with-multiple-tenants