[FIR] Support determining emptiness of an intersection type with type parameters' types

compiler/testData/diagnostics/tests/inference/upperBounds/nullableEmptyIntersection.fir.kt

@@ -0,0 +1,7 @@
+fun <T : <!FINAL_UPPER_BOUND!>String<!>> g(): T? = null
+
+fun <R> f(block: () -> R?): R? = block()
+
+fun main() {
+    <!INFERRED_TYPE_VARIABLE_INTO_EMPTY_INTERSECTION!>f<!><Int> { g() /* OK, g() is inferred into {Int & String}? */ }
+}

compiler/testData/diagnostics/tests/inference/upperBounds/nullableEmptyIntersection.kt

@@ -0,0 +1,7 @@
+fun <T : <!FINAL_UPPER_BOUND!>String<!>> g(): T? = null
+
+fun <R> f(block: () -> R?): R? = block()
+
+fun main() {
+    <!INFERRED_TYPE_VARIABLE_INTO_EMPTY_INTERSECTION_WARNING!>f<!><Int> { g() /* OK, g() is inferred into {Int & String}? */ }
+}

compiler/testData/diagnostics/tests/inference/upperBounds/nullableEmptyIntersection.txt

@@ -0,0 +1,5 @@
+package
+
+public fun </*0*/ R> f(/*0*/ block: () -> R?): R?
+public fun </*0*/ T : kotlin.String> g(): T?
+public fun main(): kotlin.Unit