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/declarations/parameters/class.kt.txt

@@ -1,6 +1,5 @@
 interface TestInterface<T : Any?> {
   interface TestNestedInterface<TT : Any?> {
-
   }
 
 }

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

@@ -42,7 +42,6 @@ interface TestInterface<T : Any?> {
   //   Mangled name: TestInterface.TestNestedInterface
   //   Public signature: /TestInterface.TestNestedInterface|null[0]
   interface TestNestedInterface<TT : Any?> {
-
   }
 
 }

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

@@ -83,6 +83,7 @@ class Test2 {
     //   Public signature: /Test2.TestInner.<init>|-8731461708390519279[0]
     //   Public signature debug description: <init>(1:0){}
     constructor(z: Z) /* primary */
+
     // CHECK:
     //   Mangled name: Test2.TestInner#<init>(1:0;kotlin.Int){}
     //   Public signature: /Test2.TestInner.<init>|7281397193015694517[0]
@@ -165,6 +166,7 @@ class Test4<T : Any?> {
   //   Public signature: /Test4.<init>|-5182794243525578284[0]
   //   Public signature debug description: <init>(kotlin.Int){}
   constructor(x: Int) /* primary */
+
   // CHECK:
   //   Mangled name: Test4#<init>(kotlin.Int;kotlin.Int){}
   //   Public signature: /Test4.<init>|-7691762014320324121[0]

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

@@ -37,6 +37,7 @@ data class Test<T : Any?> {
   //   Public signature: /Test.<init>|-7411275398527089511[0]
   //   Public signature debug description: <init>(1:0;kotlin.String){}
   constructor(x: T, y: String) /* primary */
+
   // CHECK JVM_IR:
   //   Mangled name: Test#component1(){}1:0
   //   Public signature: /Test.component1|2393470133763651536[0]

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

@@ -7,6 +7,7 @@ class Test<TT : Any?> : IBase<TT> {
   //   Public signature: /Test.<init>|-3017997426280513504[0]
   //   Public signature debug description: <init>(IBase<1:0>){}
   constructor(impl: IBase<TT>) /* primary */
+
   // CHECK:
   //   Mangled name: Test#foo(kotlin.Int){}
   //   Public signature: /Test.foo|-104159190164110731[0]
@@ -40,7 +41,6 @@ class Test<TT : Any?> : IBase<TT> {
 //   Mangled name: IBase
 //   Public signature: /IBase|null[0]
 interface IBase<T : Any?> {
-
   // CHECK:
   //   Mangled name: IBase#foo(kotlin.Int){}
   //   Public signature: /IBase.foo|-104159190164110731[0]