is possible add method propfind to enum asMethod

[freyes-lef]

Hi

my request it´s similar to #1689

In older versions of RestSharp i use this:

var response = client.ExecuteAsPost(request, "PROPFIND");

it,s possible add de PROPFIND method to call to webdav server

example:
var response = await client.ExecutePostAsync(request, Method.Propfind);

Thnks in advance

[freyes-lef]

It´s possible add the rest of methods for webdav in future previsions:

MKCOL, MOVE, LOCK, UNLOCK

Thanks

[alexeyzimarev]

I added a more generic issue #2166, let's discuss it there.