Set friend modules for android gradle test tasks

This fixes the following issues:
1. When product flavors were used, android unit tests could not refer
to internal symbols from main source set.
2. Android instrumentation tests could not refer
to internal symbols from main source set

    #KT-11166 fixed

libraries/tools/kotlin-gradle-plugin/pom.xml

@@ -66,7 +66,6 @@
         </dependency>
     </dependencies>
 
-
     <build>
         <sourceDirectory>${project.basedir}/src/main/kotlin</sourceDirectory>
         <testSourceDirectory>${project.basedir}/src/test/kotlin</testSourceDirectory>