Use footnote separator in reference.docx for docx output. (#7087)

[niszet]

For using footnote separator in reference.docx, T.P.W.Docx is updated. To use footnote separator, footnote tags which have w:type attibutes are used. For avoiding error when opening by MS Word, w:p tags are renewed without its attributes. Missing id and type are not cared in this commit. This is for the issue #7087.

[niszet]

I would like to consult about additional test for this commit. I think additional test for checking footnote separator is needed.

And, although I commented as https://github.com/jgm/pandoc/pull/7182/commits/79ed4a76e101fe8ed527badd371615d793b48b40#diff-eee63dec4cba05fb9505172f7a2d0dad5435f2be186202f9599c3c6d559c2c1eR284 , but if id or type is missing, used reference.docx should be wrong format. So maybe no need to add a error handling about lack of these attributes.

[niszet]

Sorry for a bit off-topic but I noticed the Error during the test in the log.

https://github.com/jgm/pandoc/pull/7182/checks?check_run_id=2212106262#step:7:788

  #1:                                                            Error: Circular defaults file reference in 'command/defaults7.yaml'

I don't know why this doesn't raise a FAIL for the test... (This Error also appears in my local environment)

[niszet]

Sorry, about this message https://github.com/jgm/pandoc/pull/7182#issuecomment-808889488 ,

is already explained in

https://github.com/jgm/pandoc/issues/7061

and

https://github.com/jgm/pandoc/issues/6674 . I understand this message in the test log is no problem. Sorry for bothering you.

So, I will add a test for this footnote separator update.