FIR IDE: Fix import of properties; also fix bug in alreadyHasImport

idea/idea-completion/testData/handlers/multifile/AlreadyImportedExtensionPropertyNoImport-1.kt

@@ -0,0 +1,8 @@
+// FIR_COMPARISON
+package first
+
+import second.extensionProp
+
+fun foo() {
+    "".extensi<caret>
+}

idea/idea-completion/testData/handlers/multifile/AlreadyImportedExtensionPropertyNoImport-2.kt

@@ -0,0 +1,4 @@
+package second
+
+val String.extensionProp: Int
+    get() = 1

idea/idea-completion/testData/handlers/multifile/AlreadyImportedExtensionPropertyNoImport.kt.after

@@ -0,0 +1,8 @@
+// FIR_COMPARISON
+package first
+
+import second.extensionProp
+
+fun foo() {
+    "".extensionProp<caret>
+}