Schema.Primitive respects default annotation for defaultValue (#715)

Add Schema.defaultValue to set default of a schema

tests/shared/src/test/scala/zio/schema/DefaultValueSpec.scala

@@ -300,6 +300,11 @@ object DefaultValueSpec extends ZIOSpecDefault {
         val rightSchema = Schema.either(Schema.fail("Nothing"), Schema.primitive(StandardType.StringType))
         assert(rightSchema.defaultValue)(isRight(isRight(equalTo(""))))
       }
-    )
+    ),
+    suite("default from annotation") {
+      test("default value from annotation") {
+        assert(Schema[String].defaultValue("default").defaultValue)(isRight(equalTo("default")))
+      }
+    }
   )
 }

zio-schema/shared/src/main/scala/zio/schema/Schema.scala

@@ -57,6 +57,11 @@ sealed trait Schema[A] {
    */
   def defaultValue: scala.util.Either[String, A]
 
+  /**
+   * Add a default value to this schema.
+   */
+  def defaultValue(value: A): Schema[A] = self.annotate(fieldDefaultValue(value))
+
   /**
    * Chunk of annotations for this schema
    */
@@ -562,7 +567,15 @@ object Schema extends SchemaPlatformSpecific with SchemaEquality {
 
     override def annotate(annotation: Any): Primitive[A] = copy(annotations = (annotations :+ annotation).distinct)
 
-    override def defaultValue: scala.util.Either[String, A] = standardType.defaultValue
+    private def annotatedDefaultValue = annotations.collectFirst {
+      case a if a.isInstanceOf[fieldDefaultValue[_]] => a.asInstanceOf[fieldDefaultValue[A]].value
+    }
+
+    override def defaultValue: scala.util.Either[String, A] =
+      annotatedDefaultValue match {
+        case Some(value) => Right(value)
+        case None        => standardType.defaultValue
+      }
 
     override def makeAccessors(b: AccessorBuilder): Unit = ()
   }