gnss: add GNSS assistance support

Automatically fetch the GNSS assistance data from the Web
to heavily reduce the time to acquire a GNSS lock by uploading
the assistance data to the modem.
This feature is optional and can be disabled in the configuration
as people may prefer to not download the assistance data from
the Quectel/Qualcomm servers.
Also configure the GNSS engine to optimize the performance
and power consumption.

meson.build

@@ -58,6 +58,7 @@ mgr_deps = [
     dependency('gudev-1.0'),
     dependency('libgpiod'),
     dependency('libusb-1.0'),
+    dependency('libcurl'),
     mmglib_dep,
 ]