Update Linux build docs for Arch/Ubuntu, add logging calls to Qmake

The page was not made with Arch in mind.

The currently required were tested on Manjaro, more packages may be
explicitly required due to the bare-bones nature of Arch.

Adds simple logging calls makes debugging easier.

The initial build script was basically ported over directly from
Windows. It was written because I at the time didn't understand
compiling on Linux, and the existing standards, very well.

Moving as many build components into a program specifically made for
building C++ makes everything much easier.

The old build script is still used on CI where control flow can only be
changed using environment variables.

`bear` and `clang-format` are only used on the CI, there's no reason to
include them here.

build_scripts/qt/sources.pri

@@ -58,19 +58,23 @@ win32 {
 
 unix:!macx {
     !noX11 {
+        message(X11 features enabled.)
         SOURCES += src/keyboard_input/input_sender_X11.cpp
         CONFIG += x11
         LIBS += -lXtst
     }
     else {
+        message(X11 features disabled.)
         SOURCES += src/keyboard_input/input_sender_dummy.cpp
     }
 
     !noDBUS {
+        message(DBUS features enabled.)
         SOURCES += src/media_keys/media_keys_dbus.cpp
         QT += dbus
     }
     else {
+        message(DBUS features disabled.)
         SOURCES += src/media_keys/media_keys_dummy.cpp
     }