[rfc] implement fprint "gross hack" for parallel fingerprint / password entry

[sudopluto]

rfc for @uunicorn

https://gitlab.com/mishakmak/pam-fprint-grosshack

as I am using python-validity, having the parallel fingerprint / password entry is something i miss from my old laptop, that worked with just the regular fprint stack

i am planning on porting over the "hack" to open-fprintd, but want to first ask for a blessing before I go through the whole PR process. if this is something you are not interested in adding / maintaining, I totally understand, and I will go ahead and fork the project.

either way, wish you are doing well, and thank you so much for building up the whole stack to get the fingerprint sensor working : )