set AuthenticationType of JwtBearer TokenValidationParameters

[DanielEgbers]

This PR fixes HttpContext.User.Identity.AuthenticationType not being set correctly when authenticating with JwtBearer.

Given the following endpoint and appsettings:

app.MapGet("api/me", (ClaimsPrincipal user) =>
{
    return new
    {
        user?.Identity?.AuthenticationType
    };
})

"Authentication": {
  "JwtBearer": {
      "SchemeName": "my_JwtBearer_scheme",
      ...
  },
  "ApiKey": {
      "SchemeName": "my_ApiKey_scheme",
      ...
  },
  "Basic": {
      "SchemeName": "my_Basic_scheme",
      ...
  }
}

Authenticating with Basic will return { "authenticationType": "my_Basic_scheme" }
and authenticating with ApiKey will return { "authenticationType": "my_ApiKey_scheme" }.
However authenticating with JwtBearer will currently return { "authenticationType": "AuthenticationTypes.Federation" } instead the expected { "authenticationType": "my_JwtBearer_scheme" }.

[marcominerva]

Thank you for your contribution @DanielEgbers. The fix has been merged and published on NuGet (v2.0.21).