Read and write QtGP settings from the QtTAS to gradle.properties file

Why are we doing this?

• With modern Android development patterns, using modules is a common practice. In this approach, the android project can have any arbitrary structure which the QtTAS plugin will have no idea about where to read QtGP properties from.
• Even if the QtTAS plugin knew where to read it from, there is no API in Jetbrains for working with custom gradle blocks (QtBuild {} block in our case). So we had to rely on using regex, which can cause a lot or errors.

What's the plan?

• We decided that it would be good to have a central configuration file which both the QtTAS and QtGP can access.
• This eliminates the need for the QtTAS to use regex on the build.gradle file.
• We decided to make use of the gradle.properties file which is already present in Android Projects and which the Android Gradle Plugin uses for its configurations.
• The user can manually add the Qt configurations (Project path, Qt path, etc) in that file, or the QtTAS plugin can automatically add it for them.

Definition of done

• The QtTAS plugin is able to read and write to the gradle.properties file and we can bring back the settings page, and give back the functionality to Create/Import Qt projects