Adds Client::getFolderByPath()

[Max13]

For when an accounts has multiple time the same folder name under different parent folder.

[Max13]

IMHO, Client::getFolder() should have been "by path" and not "by name" from the beginning (it's more intuitive).

So if cce49a4 is accepted, then Client::getFolderByName() should exist to prevent ambiguity, without breaking compatibility

[Webklex]

Hi @Max13 ,
thanks a lot 👍