Add possibility to interpret and fold IrStringConcatenation expression

compiler/testData/diagnostics/tests/annotations/parameters/expressions/stringTemplate.fir.kt

@@ -1,19 +0,0 @@
-package test
-
-annotation class Ann(
-        val s1: String,
-        val s2: String,
-        val s3: String,
-        val s4: String
-)
-
-val i = 1
-
-@Ann(
-    s1 = "a$i",
-    s2 = "a$i b",
-    s3 = <!NON_CONST_VAL_USED_IN_CONSTANT_EXPRESSION!>"$i"<!>,
-    s4 = "a${i}a$i"
-) class MyClass
-
-// EXPECTED: @Ann(s1 = "a1", s2 = "a1 b", s3 = "1", s4 = "a1a1")

compiler/testData/diagnostics/tests/annotations/parameters/expressions/stringTemplate.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 package test
 
 annotation class Ann(

compiler/testData/diagnostics/tests/annotations/parameters/expressions/strings.fir.kt

@@ -1,9 +0,0 @@
-package test
-
-annotation class Ann(val s1: String, val s2: String)
-
-val i = 1
-
-@Ann(s1 = "a" + "b", s2 = "a" + "a$i") class MyClass
-
-// EXPECTED: @Ann(s1 = "ab", s2 = "aa1")

compiler/testData/diagnostics/tests/annotations/parameters/expressions/strings.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 package test
 
 annotation class Ann(val s1: String, val s2: String)