False positive from UnusedImports on provideDelegate operator functions

[eskatos]

The fix for #506 in b997561 hardcoded the org.gradle.kotlin.dsl.provideDelegate import but provideDelegate operator functions aren't limited to org.gradle.kotlin.dsl and could be present in any Kotlin library.

See https://kotlinlang.org/docs/reference/delegated-properties.html#providing-a-delegate-since-11

The fix should be extended to any import of a provideDelegate operator function.

[JakeWharton]

I currently have this problem in diffuse (git SHA ac5f1aa2c8cdcbb00beb0f3515201eb583385c77) from use of the Clikt library:

https://github.com/JakeWharton/diffuse/blob/ac5f1aa2c8cdcbb00beb0f3515201eb583385c77/diffuse/src/main/kotlin/com/jakewharton/diffuse/diffuse.kt#L10

> Task :diffuse:ktlintMainSourceSetCheck FAILED
/Volumes/dev/JakeWharton/diffuse/diffuse/src/main/kotlin/com/jakewharton/diffuse/diffuse.kt:10:1: Unused import