Support cross-compilation to Windows using MinGW
## Goal
Allow developers to deploy Wireshark on Microsoft Windows using only Linux and FOSS tooling.
## Tasks
1. [x] Build a usable NSIS Windows installer using MingW-w64 and Fedora Linux
- [x] Add deployment of Qt runtime to NSIS installer
- [x] Add NSIS uninstaller
1. [x] Add Gitlab CI/CD build with MinGW cross-compilation
1. [x] Add build documentation for cross-compilation
1. [ ] Add missing dependencies upstream or to a private RPM repository
- [ ] [libssh](https://www.libssh.org/)
- [ ] [libmaxminddb](https://maxmind.github.io/libmaxminddb/)
- [ ] [libsmi](https://www.ibr.cs.tu-bs.de/projects/libsmi/)
- [ ] [lz4](https://github.com/lz4/lz4)
- [ ] [snappy](https://github.com/google/snappy)
- [ ] [Nghttp2](https://nghttp2.org/)
- [x] [Lua](https://www.lua.org/) (commit 687b24d5b3d3a386591040e5fda5f2e659f95e99)
- [ ] [SBC](https://git.kernel.org/pub/scm/bluetooth/sbc.git)
- [ ] [SpanDSP](https://www.soft-switch.org)
- [ ] [BCG729](https://www.linphone.org/technical-corner/bcg729)
- [ ] [opencore-amr](https://sourceforge.net/p/opencore-amr)
- [ ] [iLBC](https://github.com/TimothyGu/libilbc)
issue