[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/firProblems/VarInInit.sig.kt.txt

@@ -0,0 +1,27 @@
+// CHECK:
+//   Mangled name: Some
+//   Public signature: /Some|null[0]
+class Some {
+  // CHECK:
+  //   Mangled name: Some{}foo
+  //   Public signature: /Some.foo|1688079488202778848[0]
+  var foo: Int
+    // CHECK JVM_IR:
+    //   Mangled name: Some#<get-foo>(){}kotlin.Int
+    //   Public signature: /Some.foo.<get-foo>|-5521901919061670077[0]
+    // CHECK JS_IR NATIVE:
+    //   Mangled name: Some#<get-foo>(){}
+    //   Public signature: /Some.foo.<get-foo>|-2462361841367688099[0]
+    get
+    // CHECK:
+    //   Mangled name: Some#<set-foo>(kotlin.Int){}
+    //   Public signature: /Some.foo.<set-foo>|3461873232640801433[0]
+    set
+
+  // CHECK:
+  //   Mangled name: Some#<init>(kotlin.Int){}
+  //   Public signature: /Some.<init>|-5182794243525578284[0]
+  constructor(foo: Int) /* primary */
+
+}
+