Support dependencies with inline variables

[johnjohndoe]

Current state

• Dependencies with the version specified as an inline text are picked up, e.g. compile "com.squareup.okhttp3:okhttp:3.11.0" (example)
• Dependencies with the version specified as an inline variable are not picked up, e.g. compile "com.squareup.okhttp3:okhttp:$okhttpVersion" (example)

Target state

• Both, versions defined as inline text or an inline variable are picked up.

Background

• Groovy allows to use inline variables in double quoted strings. The variable is typically defined in the same .gradle file or in a separate file such as build.gradle in the root of the project or in properties.gradle which can be stored in different locations and also gets read in by gradle.
• Another common pattern is to store versions and dependencies strings in the special buildSrc/ module. Here is an example implemented in Kotlin but used from within the Groovy build.gradle files.

[johnjohndoe]

I just realized that I created an issue earlier: librariesio/libraries.io#1976