Add variance (in / out) modifier inspection #KT-11090 Fixed

idea/testData/quickfix/addVarianceModifier/.inspection

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+org.jetbrains.kotlin.idea.inspections.AddVarianceModifierInspection

idea/testData/quickfix/addVarianceModifier/Empty.kt

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+// "Add 'out' variance" "true"
+interface Empty<<caret>T>

idea/testData/quickfix/addVarianceModifier/abstractIn.kt

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+// "Add 'in' variance" "true"
+abstract class AbstractIn<<caret>T>(private val foo: T) {
+    fun bar(arg: T) = foo == arg
+}

idea/testData/quickfix/addVarianceModifier/abstractIn.kt.after

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+// "Add 'in' variance" "true"
+abstract class AbstractIn<in T>(private val foo: T) {
+    fun bar(arg: T) = foo == arg
+}

idea/testData/quickfix/addVarianceModifier/abstractOut.kt

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+// "Add 'out' variance" "true"
+abstract class AbstractOut<<caret>T> {
+    abstract val foo: T
+    private var bar = foo
+}

idea/testData/quickfix/addVarianceModifier/abstractOut.kt.after

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+// "Add 'out' variance" "true"
+abstract class AbstractOut<out T> {
+    abstract val foo: T
+    private var bar = foo
+}

idea/testData/quickfix/addVarianceModifier/empty.kt.after

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+// "Add 'out' variance" "true"
+interface Empty<out T>