HTTPRequest : When md5 is checked Embedded Resources from HTML files should be disabled

@pmouawad ([Bug 57578](https://bz.apache.org/bugzilla//show_bug.cgi?id=57578&redirect=false)):
When MD5 is checked as response is not stored, no parsing can occur.
So checking anything in "Embedded Resources from HTML files" panel won't have any effect.
I suggest we disable checkbox "Retrieve All embedded resources" when "Save response as MD5 Hash" is checked.

By the way, it seems HttpTestSampleGui uselessly implemented ItemListener as none of the addItemListeners in classes uses it. So I suggest we drop it adding this to "Incompatible changes" as subclasses may be impacted.

OS: All