IR text tests: Stable blank lines between declarations in class

Rework rendering of kt-like dump and signatures dump in order to avoid
unstable blank line between declarations of the same level:
1. No blank line for the first declaration inside the member scope of
the class.
2. Always a single blank line between each two subsequent declarations
inside the member scope of the class.

compiler/testData/ir/irText/regressions/integerCoercionToT.kt.txt

@@ -1,5 +1,4 @@
 interface CPointed {
-
 }
 
 inline fun <reified T : CPointed> CPointed.reinterpret(): T {

compiler/testData/ir/irText/regressions/integerCoercionToT.sig.kt.txt

@@ -41,7 +41,6 @@ class IdType : CPointed {
 //   Mangled name: CPointed
 //   Public signature: /CPointed|null[0]
 interface CPointed {
-
 }
 
 // CHECK:

compiler/testData/ir/irText/regressions/kt45236.sig.kt.txt

@@ -33,6 +33,7 @@ sealed class NetRequestStatus<out T : Any> {
     //   Public signature: /NetRequestStatus.Error.<init>|-1373568199086185373[0]
     //   Public signature debug description: <init>(kotlin.Throwable;1:0?){}
     constructor(error: Throwable, value: T?) /* primary */
+
     // CHECK JVM_IR:
     //   Mangled name: NetRequestStatus.Error#component1(){}kotlin.Throwable
     //   Public signature: /NetRequestStatus.Error.component1|2250146239720393392[0]

compiler/testData/ir/irText/regressions/newInferenceFixationOrder1.kt.txt

@@ -3,7 +3,6 @@ fun <X : Any?, Y : Any?> foo(): Function1<X, Y> {
 }
 
 interface Inv2<A : Any?, B : Any?> {
-
 }
 
 fun <T : Any?, R : Any?> check(x: T, y: R, f: Function1<T, R>): Inv2<T, R> {

compiler/testData/ir/irText/regressions/newInferenceFixationOrder1.sig.kt.txt

@@ -2,7 +2,6 @@
 //   Mangled name: Inv2
 //   Public signature: /Inv2|null[0]
 interface Inv2<A : Any?, B : Any?> {
-
 }
 
 // CHECK JVM_IR: