Fix Universal Outline Post and 3D character menus examples

[phi-lira]

Purpose of this PR

• Fixed OutlinePostProcessPass and 3D Character Menu.
• Converted Blit Feature to a more general DrawFullscreenFeature and made a few improvements:
  -- Now you can select source texture to be either Camera or Custom, in which you can bind a custom property Id. In case of custom texture, the pipeline will create the texture if not available.
  -- Now you can select destination texture to be either Camera or Custom. Likewise source.
  -- We now fetch the pass list from the material and show pass names availables instead of expecting a user to input an index that might be invalid.

Still there are some known issues with this feature we need to fix but I'll address those in a follow up PR:

• If blitting / drawing after post-processing the pass will not work when having Camera as either source of destination, as at this point in the pipeline the camera texture is not _CameraColorTexture anymore, it's AfterPostProcess texture.
• We don't execute the pass if the material is null, we could improve it by executing the blit with a built-in blit shader.
  

Comment to Reviewers

This PR depends on Unity-Technologies/Graphics#1861

[erikabar]

Tested with Graphics PR: Unity-Technologies/Graphics#186
Tested on Windows, OSX, Android and iOS, no issues found

[Verasl]

LGTM