codegen-java/kotlin: Fix generation of hashCode methods (#802)

codegen-java:
- use `pattern.pattern()` instead of `pattern` in hashCode method
  (consistent with equals method)

codegen-kotlin:
- use `regex.pattern` instead of `regex` in hashCode method
  (consistent with equals method)
- if a data class has a Regex property, generate not only
  an equals method but also a hashCode method

pkl-codegen-kotlin/src/test/kotlin/org/pkl/codegen/kotlin/KotlinCodeGeneratorTest.kt

@@ -561,6 +561,26 @@ class KotlinCodeGeneratorTest {
       )
   }
 
+  @Test
+  fun `data class with Regex property has custom equals and hashCode methods`() {
+    val kotlinCode =
+      generateKotlinCode(
+        """
+      module my.mod
+
+      class Person {
+        age: Int
+        name: Regex
+      }
+    """
+          .trimIndent()
+      )
+
+    assertThat(kotlinCode)
+      .contains("if (this.name.pattern != other.name.pattern) return false")
+      .contains("result = 31 * result + Objects.hashCode(this.name.pattern)")
+  }
+
   @Test
   fun `recursive types`() {
     val kotlinCode =

pkl-codegen-kotlin/src/test/resources/org/pkl/codegen/kotlin/PropertyTypes.kotlin

@@ -139,7 +139,7 @@ object Mod {
       result = 31 * result + Objects.hashCode(this.container)
       result = 31 * result + Objects.hashCode(this.container2)
       result = 31 * result + Objects.hashCode(this.other)
-      result = 31 * result + Objects.hashCode(this.regex)
+      result = 31 * result + Objects.hashCode(this.regex.pattern)
       result = 31 * result + Objects.hashCode(this.any)
       result = 31 * result + Objects.hashCode(this.nonNull)
       result = 31 * result + Objects.hashCode(this.enum)