doclicense: option to disable xmp to be compatible with pdfx about latex-packages

[TeXhackse]

auto detection can of course be used to change the mechanism to pdfx if that one is loaded.

Thing is hyperref will also ignore the data by doclicense if the field already set and throw a warning, this might confuse users. Therefore I suggest to add both. It's not a big change anyway. I'll prepare a PR tomorrow. Then you can have a look.

[ypid]

I am fine with adding options to disable loading/interacting of both of these packages with two separate options. doclicense could also check if pdfx is loaded at the end of the preamble and if yes, doclicense backs off and does not attempt to load hyperxmp. What do you think about adding this kind of auto detection? Want to give it a try in a pull request?

Ref: #63 (that you already referenced tudace/tuda_latex_templates#294). It got me into trouble after all, but nothing that cannot be solved :)

[TeXhackse]

Release is done and available via CTAN.