Make LTE Uu stats and graph work for NR too

N.B. Application of filters currently not working in tap_parameter_dialog.cpp

Have changed existing tap names "mac-lte" and "rlc-lte" to mean "mac-3gpp" and "rlc-3gpp - these now refer to both LTE an NR. Have also, for now, left LTE-specific filenames for files that can also now also deal with NR.

There will likely be several follow-up commits to address pre-existing issues noticed in the statistics and graph dialogs.