modules: add config endpoint module

modules/meson.build

modules/module-config-endpoint.c

modules/module-config-endpoint/context.c

modules/module-config-endpoint/context.h

modules/module-config-endpoint/parser-endpoint.c

modules/module-config-endpoint/parser-endpoint.h

modules/module-config-endpoint/parser-streams.c

modules/module-config-endpoint/parser-streams.h

modules/module-pipewire/audio-softdsp-endpoint.c

src/wireplumber.conf

src/wireplumber/audio-sink.endpoint

src/wireplumber/audio-source.endpoint

src/wireplumber/stream-input-audio.endpoint

src/wireplumber/stream-output-audio.endpoint

tests/modules/config-endpoint.c

tests/modules/config-endpoint/basic/audio-source.endpoint

tests/modules/config-endpoint/basic/default.streams

tests/modules/config-endpoint/endpoint-audiotestsrc.c

tests/modules/config-endpoint/endpoint-audiotestsrc.h

tests/modules/meson.build