K2 JVM: Take JVM declarations conflicting error back

Since SimpleDiagnosticsCollectorWithSuppress have been replaced by
PendingDiagnosticsCollectorWithSuppress after commit 9add6f3d55,
diagnostics need to be committed now.

#KT-54366 Fixed

compiler/testData/cli/jvm/conflictingJvmDeclarations.args

@@ -0,0 +1,4 @@
+$TESTDATA_DIR$/conflictingJvmDeclarations.kt
+-Xuse-k2
+-d
+$TEMP_DIR$

compiler/testData/cli/jvm/conflictingJvmDeclarations.kt

@@ -0,0 +1,9 @@
+class Foo {
+    val x: Int
+        get() = 42
+
+    fun getX() = 42
+
+    @JvmName("getX")
+    fun getY() = 42
+}

compiler/testData/cli/jvm/conflictingJvmDeclarations.out

@@ -0,0 +1,22 @@
+warning: ATTENTION!
+ This build uses experimental K2 compiler:
+  -Xuse-k2
+compiler/testData/cli/jvm/conflictingJvmDeclarations.kt:2:5: error: platform declaration clash: The following declarations have the same JVM signature (getX()I):
+    fun `<get-x>`(): Int defined in Foo
+    fun getX(): Int defined in Foo
+    fun getY(): Int defined in Foo
+    val x: Int
+    ^
+compiler/testData/cli/jvm/conflictingJvmDeclarations.kt:5:5: error: platform declaration clash: The following declarations have the same JVM signature (getX()I):
+    fun `<get-x>`(): Int defined in Foo
+    fun getX(): Int defined in Foo
+    fun getY(): Int defined in Foo
+    fun getX() = 42
+    ^
+compiler/testData/cli/jvm/conflictingJvmDeclarations.kt:7:5: error: platform declaration clash: The following declarations have the same JVM signature (getX()I):
+    fun `<get-x>`(): Int defined in Foo
+    fun getX(): Int defined in Foo
+    fun getY(): Int defined in Foo
+    @JvmName("getX")
+    ^
+COMPILATION_ERROR