QtGP Qt path finding improvement

Why?

Cause

• Currently examples using Qt Gradle plugin are finding the Qt path relatively from the 'app/build.gradle' file which can be confusing: file('../../../../../../../6.8.0')

Customer

Cruft

• This seems clear and the options listed below just seem more like hiding how it's done instead of making it easier to understand.

What?

Definition

• We want to clearly show how to specify the QtPath in our examples. 
• User might face a break if installation is on wrong path (Expected)

Demarcation

Dependencies

• Maybe we'll need to fix QTTA-216 for this to work