cli: use --component=NAME:{source,filter,sink}.PLUGIN.COMPCLS

Use a universal -c/--component option for all component class types,
specifying the component class type in the option's argument instead,
for example:

    Before: --source=ctf.fs
    After:  --component=source.ctf.fs

    Before: --sink=my-text:text.pretty
    After:  --component=my-text:sink.text.pretty

This provides a universal way to identify a component instance in:

* Log messages
* Information/error messages
* List of plugins and contained component classes
* Help messages
* Documentation

Then we can always refer to the ctf.fs source component class, for
example, as `source.ctf.fs` instead of all the variations:

* The ctf.fs source
* --source ctf.fs
* ctf.fs (source)

and so on.

Short option -c used to be for --connect: it's -C now.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>