Add support for string interpolation in ConfigFiles::KotlinGradle

What does this MR do and why?

Sometimes, the build.gradle.kts will have dependency versions stored in variables to be interpolated:

val arcgisVersion = "4.5.0"
val kotlinVersion = file("../kotlin-dsl/$kotlinVersionSourceFilePath").readLines().extractKotlinVersion()

dependencies { // Comment
    implementation("org.codehaus.groovy:groovy:3.+")
    testImplementation("com.google.guava:guava:29.0.1") // Inline comment

    implementation(project(":utils"))
    runtimeOnly(files("libs/a.jar", "libs/b.jar"))

    implementation("com.esri.arcgisruntime:arcgis-java:$arcgisVersion")
}

We currently don't support string interpolation, and store the version as nil.

This MR provides support for string interpolation when parsing dependencies for build.gradle.kts.

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Related to #481317 (closed)