[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/classes/kt45934.kt

@@ -1,6 +1,9 @@
 // TARGET_BACKEND: JVM
 // SKIP_KT_DUMP
 
+// SKIP_SIGNATURE_DUMP
+// ^ K2 generates an override for foo in C, K1 does not
+
 // FILE: kt45934.kt
 
 class C(client: J) : I by client