feat: StaX filter produce self-contained empty element

[miurahr]

Set Woodstox property to allow self-contained empty element in StaX filters

Pull request type

• Feature enhancement -> [enhancement]

Which ticket is resolved?

What does this PR change?

Other information

[t-cordonnier]

The idea is good but we must check what DOCX format requires. Even if in theory <x></x> and <x/> are strictly equivalent it sometimes happens that some tools (like Word, or Trados!) do not consider as such. I must do some tests before to validate it (even if strictly speaking I approve)

[miurahr]

@t-cordonnier yes or no?

[miurahr]

progress?

[t-cordonnier]

I found an example where a document containing something like <x></x> was rejected by Trados Studio while accepted by Word. So in principle I would say yes, in theory. But considering that in theory the just mentioned error should not happen, I prefer concrete tests than abstract theory. So, before validating, are you capable of giving me an example where OmegaT produces a different document after your patch than before? If yes, I will test the document against various tools and tell you wherever your change improves compatibility or can make a regression.