MRTK-Quest V1.2.0 update

[provencher]

Changes:

• Update Unity to 2019.4.12
• Update Oculus SDK to 20.1 for proper Quest 2 support (+ Integrated it into the project, removing the ignore)
• Update MRTK to latest dev branch (v2.5.1 + shader mip map fix)
• Updated example scene with elastic and color picker examples
• Fixed panning example
• Removed FFR and reduce super sampling back to 1 as Quest 2 doesn't need it
• Updated MRTK-Quest version to 1.2.