Disable m-session-settings for now, as it needs further work

This is an attempt to unclutter the API of WpProxy and
split functionality into smaller pieces, making it easier
to work with.

In this new class layout, we have the following classes:

- WpObject: base class for everything; handles activating
|           and deactivating "features"
|- WpProxy: base class for anything that wraps a pw_proxy;
 |          handles events from pw_proxy and nothing more
 |- WpGlobalProxy: handles integration with the registry

All the other classes derive from WpGlobalProxy. The reason
for separating WpGlobalProxy from WpProxy, though, is that
classes such as WpImplNode / WpSpaDevice can also derive from
WpProxy now, without interfacing with the registry.

All objects that come with an "info" structure and have properties
and/or params also implement the WpPipewireObject interface. This
provides the API to query properties and get/set params. Essentially,
this is implemented by all classes except WpMetadata (pw_metadata
does not have info)

This interface is implemented on each object separately, using
a private "mixin", which is a set of vfunc implementations and helper
functions (and macros) to facilitate the implementation of this interface.

A notable difference to the old WpProxy is that now features can be
deactivated, so it is possible to enable something and later disable
it again.

This commit disables modules, tests, tools, etc, to avoid growing the
patch more, while ensuring that the project compiles.

meson.build:
When the 'wrap_mode' option is set to 'nodownload' use a system version
of cpptoml. This does not require using git and having a network
connection during build, which is important for Linux packaging
infrastructure.

subprojects/cpptoml.wrap:
Pin revision to last release tag (v0.1.1).

lib/wptoml/*.cpp:
Remove 'include/' prefix from all cpptoml related includes, at is not
required.

Closes #17

    - due to usage of Reference-counted-data in lib/wptoml/array.cpp
      (requires >= 2.58, see https://developer.gnome.org/glib/stable/glib-Reference-counted-data.html)
    - and usage of G_GNUC_FALLTHROUGH in lib/wp/object-interest.c
      (requires 2.60, see https://developer.gnome.org/glib/stable/glib-Miscellaneous-Macros.html#G-GNUC-FALLTHROUGH:CAPS

)

Signed-off-by: Martin Koch, ESE GmbH <martin.koch@ese.de>

and in case it's missing, also #define some things to make compilation work,
since this is only available in a pipewire branch right now

Currently all it does is that it prints the properties
of all device nodes (Audio/Source & Audio/Sink), which
is useful for editing the configuration files

next version is going to be 0.2 from this branch

This allows loading of config and modules when deployed in
the target system without setting environment variables.