build: Port to meson build system

meson is a build system focused on speed an ease of use, which helps speeding up the software development. This patch adds meson support along autotools.

Although the entire project can be built in the same way as autotools does, there are two issues:

• gtkdoc documentation can be fully generated but it fails when using normal building steps. This is because the libqmi-glib-sections.txt is not properly generated. There is an open question in meson's google group about it. To build gtkdoc documentation properly, libqmi-glib-sections.txt file must be build separately and then build documentation.
• Although it's not an important issue, file links have been created for qfu-enum-types.[ch].template and qmi-enum-types-private.[ch].template template files. This is because meson uses the template file names for final file names.