tools: tplgtool2: Support for feature topologies and merging of topologies

[ujfalusi]

This PR builds on #1361 (which will be closed):
It adds support for handling of feature topologies: fragment topologies which plugs into existing function or monolithic topology.

./tools/tplgtool2.py -D /tmp/ -d pcm,graph <path to sof-sdca-amp-ref-dai.tplg>

pcm_id=12;name=Speaker Echo Reference;type=capture ;rate_min=     0;rate_max=     0;ch_min=2;ch_max=2;fmts=S16_LE S24_LE S32_LE
WARNING: graph-only node(s) without matching widget: module-copier.21.22

It also adds a new command line parameter: --merge which will attempt to merge the topology files specified as command line parameters into a single view with noting the source of widgets and merge point(s):

./tools/tplgtool2.py -D /tmp/ -d pcm,graph --merge <path to sof-sdca-2amp-id2.tplg> <path to sof-sdca-amp-ref-dai.tplg>

pcm_id= 2;name=Speaker               ;type=playback;rate_min=     0;rate_max=     0;ch_min=2;ch_max=2;fmts=S16_LE S24_LE S32_LE
pcm_id=35;name=Deepbuffer Speaker    ;type=playback;rate_min=     0;rate_max=     0;ch_min=2;ch_max=2;fmts=S16_LE S24_LE S32_LE
pcm_id=12;name=Speaker Echo Reference;type=capture ;rate_min=     0;rate_max=     0;ch_min=2;ch_max=2;fmts=S16_LE S24_LE S32_LE