Adding some ucfirst, substr and strtolower expressions

Author: sebprt

src/StringExpressionLanguageProvider.php

@@ -12,7 +12,9 @@ public function getFunctions(): array
         return [
             ExpressionFunction::fromPhp('sprintf', 'format'),
             ExpressionFunction::fromPhp('trim', 'trim'),
-            ExpressionFunction::fromPhp('str_replace', 'replace'),
+            ExpressionFunction::fromPhp('ucfirst'),
+            ExpressionFunction::fromPhp('strtolower'),
+            ExpressionFunction::fromPhp('substr'),
             new FileName('fileName'),
             new DateTime('dateTime'),
             new FormatDate('formatDate'),