webos_version: Add a bbclass for parsing WEBOS_VERSION

:Release Notes:
Split off the functions that parse WEBOS_VERSION into a separate bbclass
so that they can be used by other bbclasses.

:Detailed Notes:

:Testing Performed:
"make webos-image" succeeded.

:QA Notes:
No change to image.

:Build Notes:
This change will invalidate the sstate of all webOS components.

:Issues Addressed:
[GF-9265] Develop a scheme so that binary components that contain kernel
          modules don't need to depend on virtual/kernel

Open-webOS-DCO-1.0-Signed-off-by: Herb Kuta <herb.kuta@lge.com>
Change-Id: I024838b847d131ecad74d5b33f3d78fac804840e
Reviewed-on: https://g2g.palm.com/3718
Reviewed-by: Herb Kuta <herb.kuta@lge.com>
Tested-by: Herb Kuta <herb.kuta@lge.com>
Reviewed-by: Susan Montooth <susan.montooth@lge.com>