Purl Encoding/Decoding bug

[thepl4n]

As per purl specification, purl URL should conform to the URL definitions or specifications of rfc3986. Current implementation uses WebUtility.UrlEncode() and WebUtility.UrlDecode() which does not follow rfc3986 specification.
Example - 

PackageURL purl = new PackageURL("docker", "ruby advisory db check");
Console.WriteLine(purl.ToString());
// This code produces the following output:
// pkg:docker/ruby+advisory+db+check

As here we can see the WebUtility.UrlEncode() encodes spaces as + but as per rfc3986 it should be encoded as %20. If we look other implementations of purl (JAVA, JS) those implementations encode spaces as %20. There's incompatibility with other implementations when they decode purl encoded by this dotnet implementation.