[FIR] Save IR dumps to .ir.txt files instead of .txt in tests

This is needed to avoid clashes between different dumps from different
  handlers

compiler/testData/ir/irText/stubs/builtinMap.kt.txt

@@ -7,4 +7,3 @@ fun <K1 : Any?, V1 : Any?> Map<out K1, V1>.plus(pair: Pair<K1, V1>): Map<K1, V1>
 )
   }
 }
-

compiler/testData/ir/irText/stubs/constFromBuiltins.fir.kt.txt

@@ -1,4 +1,3 @@
 val test: Int
   field = Companion.#MIN_VALUE
   get
-

compiler/testData/ir/irText/stubs/constFromBuiltins.kt.txt

@@ -1,4 +1,3 @@
 val test: Int
   field = -2147483648
   get
-

compiler/testData/ir/irText/stubs/genericClassInDifferentModule.kt.txt

@@ -50,4 +50,3 @@ class Derived1<T : Any?> : Base<T> {
     }
 
 }
-

compiler/testData/ir/irText/stubs/javaConstructorWithTypeParameters.fir.kt.txt

@@ -13,4 +13,3 @@ fun test3(j1: J1<Any>): J2<@FlexibleNullability Int?, Any> {
 fun test4(j1: J1<Any>): J2<@FlexibleNullability Int?, Any> {
   return j1.J2<@FlexibleNullability Int?, @FlexibleNullability Int?>(x2 = 1)
 }
-

compiler/testData/ir/irText/stubs/javaConstructorWithTypeParameters.kt.txt

@@ -13,4 +13,3 @@ fun test3(j1: J1<Any>): J2<Int, Any> {
 fun test4(j1: J1<Any>): J2<Int, Any> {
   return j1.J2<@FlexibleNullability Int?, @FlexibleNullability Int?>(x2 = 1)
 }
-

compiler/testData/ir/irText/stubs/javaEnum.kt.txt

@@ -1,4 +1,3 @@
 val test: JEnum
   field = JEnum.ONE
   get
-

compiler/testData/ir/irText/stubs/javaInnerClass.kt.txt

@@ -10,4 +10,3 @@ class Test1 : J {
     get
 
 }
-

compiler/testData/ir/irText/stubs/javaMethod.kt.txt

@@ -1,4 +1,3 @@
 fun test(j: J) {
   return j.bar()
 }
-

compiler/testData/ir/irText/stubs/javaNestedClass.kt.txt

@@ -1,4 +1,3 @@
 fun test(jj: JJ) {
   return jj.foo()
 }
-

compiler/testData/ir/irText/stubs/javaStaticMethod.kt.txt

@@ -1,4 +1,3 @@
 fun test() {
   return bar()
 }
-

compiler/testData/ir/irText/stubs/javaSyntheticProperty.kt.txt

@@ -1,4 +1,3 @@
 val test: @FlexibleNullability String?
   field = J().getFoo()
   get
-

compiler/testData/ir/irText/stubs/jdkClassSyntheticProperty.kt.txt

@@ -2,4 +2,3 @@ val Class<*>.test: @FlexibleNullability Array<out @FlexibleNullability Field?>?
   get(): @FlexibleNullability Array<out @FlexibleNullability Field?>? {
     return <this>.getDeclaredFields<@FlexibleNullability Any?>()
   }
-

compiler/testData/ir/irText/stubs/kotlinInnerClass.kt.txt

@@ -1,4 +1,3 @@
 fun test(inner: Inner) {
   return inner.foo()
 }
-

compiler/testData/ir/irText/stubs/simple.fir.kt.txt

@@ -1,4 +1,3 @@
 val test: Int
   field = 2.plus(other = 2)
   get
-

compiler/testData/ir/irText/stubs/simple.kt.txt

@@ -1,4 +1,3 @@
 val test: Int
   field = 4
   get
-