[FIR] Update/add extended checker tests

compiler/fir/analysis-tests/testData/extendedCheckers/RedundantCallOfConversionMethod/nullable.kt

@@ -1,5 +1,5 @@
 // WITH_RUNTIME
 // IS_APPLICABLE: false
 fun foo(s: String?) {
-    val t: String = s.toString()
+    val <!UNUSED_VARIABLE!>t<!>: String = s.toString()
 }

compiler/fir/analysis-tests/testData/extendedCheckers/RedundantCallOfConversionMethod/nullable2.kt

@@ -3,5 +3,5 @@
 data class Foo(val name: String)
 
 fun nullable2(foo: Foo?) {
-    val s: String = foo?.name.toString()
+    val <!UNUSED_VARIABLE!>s<!>: String = foo?.name.toString()
 }

compiler/fir/analysis-tests/testData/extendedCheckers/RedundantCallOfConversionMethod/safeString2.kt

@@ -2,5 +2,5 @@
 data class Foo(val name: String)
 
 fun test(foo: Foo?) {
-    val s: String? = foo?.name?.<!REDUNDANT_CALL_OF_CONVERSION_METHOD!>toString()<!>
+    val <!UNUSED_VARIABLE!>s<!>: String? = foo?.name?.<!REDUNDANT_CALL_OF_CONVERSION_METHOD!>toString()<!>
 }

compiler/fir/analysis-tests/testData/extendedCheckers/RedundantCallOfConversionMethod/uByte.kt

@@ -1,4 +1,4 @@
 // WITH_RUNTIME
 fun test(i: UByte) {
-    val foo = i.<!REDUNDANT_CALL_OF_CONVERSION_METHOD!>toUByte()<!>
+    val <!UNUSED_VARIABLE!>foo<!> = i.<!REDUNDANT_CALL_OF_CONVERSION_METHOD!>toUByte()<!>
 }

compiler/fir/analysis-tests/testData/extendedCheckers/RedundantCallOfConversionMethod/uInt.kt

@@ -1,4 +1,4 @@
 // WITH_RUNTIME
 fun test(i: UInt) {
-    val foo = i.<!REDUNDANT_CALL_OF_CONVERSION_METHOD!>toUInt()<!>
+    val <!UNUSED_VARIABLE!>foo<!> = i.<!REDUNDANT_CALL_OF_CONVERSION_METHOD!>toUInt()<!>
 }

compiler/fir/analysis-tests/testData/extendedCheckers/RedundantCallOfConversionMethod/uLong.kt

@@ -1,4 +1,4 @@
 // WITH_RUNTIME
 fun test(i: ULong) {
-    val foo = i.<!REDUNDANT_CALL_OF_CONVERSION_METHOD!>toULong()<!>
+    val <!UNUSED_VARIABLE!>foo<!> = i.<!REDUNDANT_CALL_OF_CONVERSION_METHOD!>toULong()<!>
 }

compiler/fir/analysis-tests/testData/extendedCheckers/RedundantCallOfConversionMethod/uShort.kt

@@ -1,4 +1,4 @@
 // WITH_RUNTIME
 fun test(i: UShort) {
-    val foo = i.<!REDUNDANT_CALL_OF_CONVERSION_METHOD!>toUShort()<!>
+    val <!UNUSED_VARIABLE!>foo<!> = i.<!REDUNDANT_CALL_OF_CONVERSION_METHOD!>toUShort()<!>
 }