This string shows the runtime version of the ModemManager daemon.

https://gitlab.freedesktop.org/mobile-broadband/ModemManager/issues/94

This patch fixes the following compiler warning:

mmcli-output.c:783:19: error: implicitly declaring library function 'strlen' with type 'unsigned long (const char *)' [-Werror,-Wimplicit-function-declaration]
            aux = strlen (section_infos[field_infos[item_l->field].section].name);
                  ^

This patch fixes the following issue with string conversion of a MMCallStateReason enum:

mmcli-call.c:160:88: error: implicit conversion from enumeration type 'MMCallStateReason' to different enumeration type 'MMCallState' [-Werror,-Wenum-conversion]
    mmcli_output_string (MMC_F_CALL_PROPERTIES_STATE_REASON, mm_call_state_get_string (mm_call_get_state_reason (call)));
                                                             ~~~~~~~~~~~~~~~~~~~~~~~~  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In addition to the standard human-friendly output, we now allow a
machine-friendly key-value pair output, much easier to parse and use
by programs that look at the mmcli output.

This new key-value pair output should be treated as API from now on, so
third-party programs can assume the output is compatible from one
release to another.

The --location-get action provides full location information from all
sources, which is better than per-source actions, as those were anyway
using the same API method to load location information as the global
one.

The Simple.GetStatus() method is useful for simple DBus clients that
don't need all the information associated to the modem, just the most
important bits. But, in our case, the information provided by this
method is already given by the standard modem info output, so it is
totally redundant.

This method is completely unnecessary as we have the readable Bearers
property already in place, so let's deprecate it.

Worth noting that the mm_modem_list_bearers() async/sync methods in
libmm-glib were not really using the ListBearers() method anyway, they
are using the property directly. These methods are NOT deprecated,
because they allow us to get a list of MMBearer objects, instead of
just the list of DBus paths that we get when reading the Bearers
property directly.

We also remove --list-bearers from the mmcli operation list as we have
already the same information in the standard modem output.

Each group of items should have a separator.

At this point we want the values enclosed between single quotes,
e.g. so that the fields are parsed easier by scripts.

This issue will not have any practical relevance as soon as the
key-value pair output support is merged.