va: caps: Make the template raw video caps classified by features.

va: caps: Make the template raw video caps classified by features.

The current output of raw video caps is not good. When we have multi
profiles and each profile support different formats, the output of
gst-inspect may like:

 SRC template: 'src'
 Availability: Always
 Capabilities:
   video/x-raw(memory:VAMemory)
         width: [ 1, 16384 ]
         height: [ 1, 16384 ]
         format: NV12
   video/x-raw
         width: [ 1, 16384 ]
         height: [ 1, 16384 ]
         format: NV12
   video/x-raw(memory:VAMemory)
         width: [ 1, 16384 ]
         height: [ 1, 16384 ]
         format: P010_10LE
   video/x-raw
         width: [ 1, 16384 ]
         height: [ 1, 16384 ]
         format: P010_10LE
   video/x-raw(memory:VAMemory)
         width: [ 1, 16384 ]
         height: [ 1, 16384 ]
         format: P012_LE
   video/x-raw
         width: [ 1, 16384 ]
         height: [ 1, 16384 ]
         format: P012_LE

The gst_caps_simplify does not classify the caps by same features, but
just leave them interweaved. We need to handle them manually here, the
result should be:

  SRC template: 'src'
  Availability: Always
  Capabilities:
    video/x-raw
          width: [ 1, 16384 ]
          height: [ 1, 16384 ]
          format: { (string)P010_10LE, (string)P012_LE, (string)NV12 }
    video/x-raw(memory:VAMemory)
          width: [ 1, 16384 ]
          height: [ 1, 16384 ]
          format: { (string)P010_10LE, (string)P012_LE, (string)NV12 }

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/2456>