[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/expressions/extFunInvokeAsFun.sig.kt.txt

@@ -0,0 +1,10 @@
+// CHECK:
+//   Mangled name: #with1(kotlin.Any?;kotlin.Function1<kotlin.Any?,kotlin.Unit>){}
+//   Public signature: /with1|7457831097191590523[0]
+fun with1(receiver: Any?, block: @ExtensionFunctionType Function1<Any?, Unit>): Unit
+
+// CHECK:
+//   Mangled name: #with2(kotlin.Any?;kotlin.Function1<kotlin.Any?,kotlin.Unit>){}
+//   Public signature: /with2|-8465193088240547938[0]
+fun with2(receiver: Any?, block: @ExtensionFunctionType Function1<Any?, Unit>): Unit
+