Enable VC1 decoder in MSDK plugin.

VC1 enablement is not straightforward like other codecs because of the input stream formats supported by MediaSDK.

* Simple & Main profile (WMV3)

We can enable Simple and Main profile decode with the usage of vc1parse in the pipeline. MSDK expecting in-stream sequence layer (SMPTE 421M Annex L, Table 265) for simple and main profile.

The decodebin/playbin won't work because: 
1: most of the asf streams output codec-data with 4 bytes sequence header (Table SMPTE 421M Annex L 263)
2: vc1parse is not yet an autoplugging element in the pipeline.
3: we don't have format conversion support in msdkvc1dec yet.

* Advanced Profile (WVC1)

Adding support for WVC1 requires more changes in msdk base decoder because:
The current implementation of msdk base decoder expecting a full frame at the input, which mandates a parser before the decoder in many cases(eg: avc decoder only supports "byte-stream+au"). So there is no global mfxBitstream tacking (no support for bitstream appending to the same mfxBitstream) is enabled.