loading directory with .xml test files

**User story**
As a tester, I want to be able load all xml tests from a directory, so no java code modification is needed when adding additional tests.

**Additional context**
I was trying something like
```
@CitrusTestSource(type=TestLoader.XML, packageScan="file:mytestdir" ....
```
with little success. I would like to see such a functionality built in (or best practice in documentation/samples to achieve this)