Support additional Gradle configurations

Our projects often times have integration tests and we use a Gradle configuration called integrationTest. The source for these tests is usually located in a src/integrationTest/java directory. Example:

my-subproject/
  build.gradle
  src/
    integrationTest/
      java/
        com/ ...
    main/
      java/
        com/ ...
build.gradle
settings.gradle

In my-subproject/build.gradle the dependencies are defined akin to

dependencies {
    implementation 'com.fasterxml.jackson.dataformat:jackson-dataformat-yaml'
    integrationTestImplementation 'org.junit.jupiter:junit-jupiter'
}

Right now, this means that IntelliSense will not be able to find symbols from the junit-jupiter dependency while editing code in the integrationTest directory. It appears to treat these source files as part of the default configuration.