There is a limitation of libreadline where no context/userdata
can be passed to completion functions. Thi affects iwctl since
the entity value isn't known to completion functions.
Workarounds such as getting the default device are employed but
its not a great solution.
Instead hack around this limitation by parsing the prompt to
extract the entity (second arg). Then use a generic match function
given to readline which can call the actual match function and
include the entity.
The table header needs to be adjusted to include spaces between
columns.
The 'adapter list' command was also updated to shorted a few
columns which were quite long for the data that is actually displayed.
This function now takes an extra argument 'extra_interface'. When
non-NULL, the property match is furthered filtered by checking whether
the proxy_interface on the given path also contains an interface of type
'extra_interface'
