Configure IdentityModel request message & configure all http clients.

[maliming]

Related #4062

This allow configure all the dynamic http client and configure the request message of the IdentityModel extension method. It can make httpclient support http 2.

example:

Configure<AbpHttpClientOptions>(options =>
{
	options.HttpClientActions.Add(clientName =>
	{
		if (clientName == "MyClient")
		{
			return c => c.DefaultRequestVersion = HttpVersion.Version10;
		}

		return c => c.DefaultRequestVersion = HttpVersion.Version20;
	});
}

Configure<IdentityModelHttpRequestMessageOptions>(options =>
{
	options.ConfigureHttpRequestMessage = request => request.Version = HttpVersion.Version20;
});

[hikalkan]

Thanks for the solution.