[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/errors/suppressedNonPublicCall.kt.txt

@@ -13,4 +13,3 @@ class C {
 inline fun C.foo() {
   <this>.bar()
 }
-

compiler/testData/ir/irText/errors/unresolvedReference.fir.kt.txt

@@ -1,16 +0,0 @@
-val test1: ErrorType
-  field = error("") /* ErrorCallExpression */
-  get
-
-val test2: ErrorType
-  field = error("") /* ErrorCallExpression */
-  get
-
-val test3: ErrorType
-  field = error("") /* ErrorCallExpression */56;
-  get
-
-val test4: ErrorType
-  field = error("") /* ErrorCallExpression */error("") /* ErrorExpression */;
-  get
-

compiler/testData/ir/irText/errors/unresolvedReference.fir.txt

@@ -1,39 +0,0 @@
-FILE fqName:<root> fileName:/unresolvedReference.kt
-  PROPERTY name:test1 visibility:public modality:FINAL [val]
-    FIELD PROPERTY_BACKING_FIELD name:test1 type:IrErrorType(null) visibility:private [final,static]
-      EXPRESSION_BODY
-        ERROR_CALL 'Unresolved reference: <Unresolved name: unresolved>#' type=IrErrorType(null)
-    FUN DEFAULT_PROPERTY_ACCESSOR name:<get-test1> visibility:public modality:FINAL <> () returnType:IrErrorType(null)
-      correspondingProperty: PROPERTY name:test1 visibility:public modality:FINAL [val]
-      BLOCK_BODY
-        RETURN type=kotlin.Nothing from='public final fun <get-test1> (): IrErrorType(null) declared in <root>'
-          GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:test1 type:IrErrorType(null) visibility:private [final,static]' type=IrErrorType(null) origin=null
-  PROPERTY name:test2 visibility:public modality:FINAL [val]
-    FIELD PROPERTY_BACKING_FIELD name:test2 type:IrErrorType(null) visibility:private [final,static]
-      EXPRESSION_BODY
-        ERROR_CALL 'Unresolved reference: <Unresolved name: unresolved>#' type=IrErrorType(null)
-    FUN DEFAULT_PROPERTY_ACCESSOR name:<get-test2> visibility:public modality:FINAL <> () returnType:IrErrorType(null)
-      correspondingProperty: PROPERTY name:test2 visibility:public modality:FINAL [val]
-      BLOCK_BODY
-        RETURN type=kotlin.Nothing from='public final fun <get-test2> (): IrErrorType(null) declared in <root>'
-          GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:test2 type:IrErrorType(null) visibility:private [final,static]' type=IrErrorType(null) origin=null
-  PROPERTY name:test3 visibility:public modality:FINAL [val]
-    FIELD PROPERTY_BACKING_FIELD name:test3 type:IrErrorType(null) visibility:private [final,static]
-      EXPRESSION_BODY
-        ERROR_CALL 'Unresolved reference: <Unresolved name: unresolved>#' type=IrErrorType(null)
-          CONST Int type=kotlin.Int value=56
-    FUN DEFAULT_PROPERTY_ACCESSOR name:<get-test3> visibility:public modality:FINAL <> () returnType:IrErrorType(null)
-      correspondingProperty: PROPERTY name:test3 visibility:public modality:FINAL [val]
-      BLOCK_BODY
-        RETURN type=kotlin.Nothing from='public final fun <get-test3> (): IrErrorType(null) declared in <root>'
-          GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:test3 type:IrErrorType(null) visibility:private [final,static]' type=IrErrorType(null) origin=null
-  PROPERTY name:test4 visibility:public modality:FINAL [val]
-    FIELD PROPERTY_BACKING_FIELD name:test4 type:IrErrorType(null) visibility:private [final,static]
-      EXPRESSION_BODY
-        ERROR_CALL 'Unresolved reference: <Ambiguity: times, [kotlin/Int.times, kotlin/Int.times, kotlin/Int.times, kotlin/Int.times, kotlin/Int.times, kotlin/Int.times]>#' type=IrErrorType(null)
-          ERROR_EXPR 'No right operand' type=IrErrorType(null)
-    FUN DEFAULT_PROPERTY_ACCESSOR name:<get-test4> visibility:public modality:FINAL <> () returnType:IrErrorType(null)
-      correspondingProperty: PROPERTY name:test4 visibility:public modality:FINAL [val]
-      BLOCK_BODY
-        RETURN type=kotlin.Nothing from='public final fun <get-test4> (): IrErrorType(null) declared in <root>'
-          GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:test4 type:IrErrorType(null) visibility:private [final,static]' type=IrErrorType(null) origin=null

compiler/testData/ir/irText/errors/unresolvedReference.kt.txt

@@ -13,4 +13,3 @@ val test3: ErrorType
 val test4: ErrorType
   field = error("") /* ErrorExpression */
   get
-