CI: Add MSYS2 zip package

[jtxa]

As requested by @marcows the documentation should be built on MSYS2 to make sure, that it works in this environment.
The workflow now includes a build all after doing the tests.

Packaging the zip and upload it as artifact was added as bonus.
The WIX package had several error messages, so that's out of scope for this PR.

As the documentation build did not work, I first splitted the PDF generation into 3 separate step, to be absolutely sure, that the groff call fails.
The only functional change of that split is, that the groff generated ps file is now kept instead of being deleted.

The observed problem was, that the file to be included by groff/soelim contained the carriage return as part of its filename.
This must be caused by the workflows checkout actions, which most probably uses Git for Windows which does CRLF checkouts by default.

To be independent from user git settings, this PR also includes a .gitattribute file that explicitly sets LF eol for all files processed by groff. Also the shell and awk scripts shall use always LF.
Editorconfig has been updated to match that behaviour.

[sierrafoxtrot]

This looks great Josef. Leaving the .ps in place does not harm and it will help in future when tracking down other doco compile issues. I really should have thought of doing this rather than manually crafting soelim and groff commands.

I could never get WIX installed due to its reliance on some ancient windows runtime (hence the move to NSIS for the 1.65 release). But as it stands (on my local windows machine at least), I can still build the ZIP archive and NSIS installer .exe so we may not need to add WIX unless it offers something additional such as supporting old platforms.