[IR] Dump IdSignatures and mangled names in irText tests

The reason #1 for this feature is that we want to test IdSignatures
generated for declarations. Currently, there is no (easy) way to ensure
that a change in the signature building logic doesn't cause any breaking
changes wrt klibs.

Now, most IdSignatures include hashed mangled names in them, so even if
we catch a regression where the included hash changes, there would be no
way of knowing immediately what caused it, unless we'd also have mangled
names in the expectations.

The reason #2 is to test the manglers themselves. Currently, there are
no tests for them. They heavily duplicate each other, this is already
causing issues (see KT-57427) that would be very hard to catch without
these tests.

^KT-58238 Fixed

compiler/testData/ir/irText/declarations/parameters/genericInnerClass.sig.kt.txt

@@ -0,0 +1,27 @@
+// CHECK:
+//   Mangled name: Outer
+//   Public signature: /Outer|null[0]
+class Outer<T1 : Any?> {
+  // CHECK:
+  //   Mangled name: Outer.Inner
+  //   Public signature: /Outer.Inner|null[0]
+  inner class Inner<T2 : Any?> {
+    // CHECK:
+    //   Mangled name: Outer.Inner#<init>(){}
+    //   Public signature: /Outer.Inner.<init>|-5645683436151566731[0]
+    constructor() /* primary */
+
+    // CHECK:
+    //   Mangled name: Outer.Inner#foo(2:0;1:0){}
+    //   Public signature: /Outer.Inner.foo|615406329799946108[0]
+    fun foo(x1: T1, x2: T2): Unit
+
+  }
+
+  // CHECK:
+  //   Mangled name: Outer#<init>(){}
+  //   Public signature: /Outer.<init>|-5645683436151566731[0]
+  constructor() /* primary */
+
+}
+