Allow to toInt() to parse a string including "__" (#578)

Fix the issue where String#toInt() cannot parse a Int string
including sequence of "_" like "1_2__3___".

pkl-core/src/main/java/org/pkl/core/stdlib/base/StringNodes.java

@@ -768,7 +768,7 @@ public final class StringNodes {
     @Specialization
     protected long eval(String self) {
       try {
-        return Long.parseLong(self);
+        return Long.parseLong(self.replaceAll("_", ""));
       } catch (NumberFormatException e) {
         throw exceptionBuilder()
             .evalError("cannotParseStringAs", "Int")
@@ -783,7 +783,7 @@ public final class StringNodes {
     @Specialization
     protected Object eval(String self) {
       try {
-        return Long.parseLong(self);
+        return Long.parseLong(self.replaceAll("_", ""));
       } catch (NumberFormatException e) {
         return VmNull.withoutDefault();
       }

pkl-core/src/test/files/LanguageSnippetTests/input/api/string.pkl

@@ -225,6 +225,8 @@ examples {
   ["toInt()"] {
     "123".toInt()
     "-123".toInt()
+    "1_2__3___".toInt()
+    "-1_2__3___".toInt()
     "0".toInt()
     "-0".toInt()
     module.catch(() -> "1.2".toInt())
@@ -236,6 +238,8 @@ examples {
   ["toIntOrNull()"] {
     "123".toIntOrNull()
     "-123".toIntOrNull()
+    "1_2__3___".toInt()
+    "-1_2__3___".toInt()
     "0".toIntOrNull()
     "-0".toIntOrNull()
     "1.2".toIntOrNull()

pkl-core/src/test/files/LanguageSnippetTests/output/api/string.pcf

@@ -181,6 +181,8 @@ examples {
     List(97, 98, 99, 100, 101, 102, 103)
   }
   ["toInt()"] {
+    123
+    -123
     123
     -123
     0
@@ -191,6 +193,8 @@ examples {
     "Cannot parse string as `Int`. String: \"abc\""
   }
   ["toIntOrNull()"] {
+    123
+    -123
     123
     -123
     0