Fix handling of characters in "convert to string template"

So #KT-23045 Fixed
So #KT-23046 Fixed

idea/testData/intentions/convertToStringTemplate/escapedQuote.kt

@@ -0,0 +1,4 @@
+// IS_APPLICABLE: false
+// SKIP_ERRORS_BEFORE
+// SKIP_ERRORS_AFTER
+val foo = '\"' + "foo"<caret>

idea/testData/intentions/convertToStringTemplate/escapedQuote2.kt

@@ -0,0 +1 @@
+val foo = "foo" + '\"'<caret>

idea/testData/intentions/convertToStringTemplate/escapedQuote2.kt.after

@@ -0,0 +1 @@
+val foo = "foo\""

idea/testData/intentions/convertToStringTemplate/invalidChar.kt.after

@@ -1,2 +1,2 @@
 // DISABLE-ERRORS
-val foo = "foo \"bar \"\""<caret>
+val foo = "foo${' "'}bar${' ""'}"

idea/testData/intentions/convertToStringTemplate/newLine.kt

@@ -0,0 +1 @@
+val foo = "\n\n" + '\n'<caret>

idea/testData/intentions/convertToStringTemplate/newLine.kt.after

@@ -0,0 +1 @@
+val foo = "\n\n\n"