feat: implement dropWhile function

Drops elements from the source as long as the predicate is satisfied.
Note the if predicate fails then subsequent elements are no longer
dropped even if they could still satisfy it. Examples:

  Source.empty[Int].dropWhile(_ > 3).toList          // List()
  Source.fromValues(1, 2, 3).dropWhile(_ < 3).toList // List(3)
  Source.fromValues(1, 2, 1).dropWhile(_ < 2).toList // List(2, 1)

core/src/main/scala/ox/channels/SourceOps.scala

@@ -159,6 +159,25 @@ trait SourceOps[+T] { this: Source[T] =>
     */
   def drop(n: Int)(using Ox, StageCapacity): Source[T] = transform(_.drop(n))
 
+  /** Drops elements from the source as long as predicate `f` is satisfied (returns `true`). Note that once the predicate `f` is not
+    * satisfied (returns `false`) no elements are dropped from the source even if they could still satisfy it.
+    *
+    * @param f
+    *   A predicate function.
+    * @example
+    *   {{{
+    *   import ox.*
+    *   import ox.channels.Source
+    *
+    *   scoped {
+    *     Source.empty[Int].dropWhile(_ > 3).toList          // List()
+    *     Source.fromValues(1, 2, 3).dropWhile(_ < 3).toList // List(3)
+    *     Source.fromValues(1, 2, 1).dropWhile(_ < 2).toList // List(2, 1)
+    *   }
+    *   }}}
+    */
+  def dropWhile(f: T => Boolean)(using Ox, StageCapacity): Source[T] = transform(_.dropWhile(f))
+
   def filter(f: T => Boolean)(using Ox, StageCapacity): Source[T] = transform(_.filter(f))
 
   def transform[U](f: Iterator[T] => Iterator[U])(using Ox, StageCapacity): Source[U] =

core/src/test/scala/ox/channels/SourceOpsDropWhileTest.scala

@@ -0,0 +1,34 @@
+package ox.channels
+
+import org.scalatest.flatspec.AnyFlatSpec
+import org.scalatest.matchers.should.Matchers
+import ox.*
+
+class SourceOpsDropWhileTest extends AnyFlatSpec with Matchers {
+  behavior of "Source.drop"
+
+  it should "not drop from the empty source" in scoped {
+    val s = Source.empty[Int]
+    s.dropWhile(_ > 0).toList shouldBe List.empty
+  }
+
+  it should "drop elements from the source while predicate is true" in scoped {
+    val s = Source.fromValues(1, 2, 3)
+    s.dropWhile(_ < 3).toList shouldBe List(3)
+  }
+
+  it should "drop elements from the source until predicate is true and then emit subsequent ones" in scoped {
+    val s = Source.fromValues(1, 2, 3, 2)
+    s.dropWhile(_ < 3).toList shouldBe List(3, 2)
+  }
+
+  it should "not drop elements from the source if predicate is false" in scoped {
+    val s = Source.fromValues(1, 2, 3)
+    s.dropWhile(_ > 3).toList shouldBe List(1, 2, 3)
+  }
+
+  it should "not drop elements from the source when predicate is false for first or more elements" in scoped {
+    val s = Source.fromValues(1, 4, 5)
+    s.dropWhile(_ > 3).toList shouldBe List(1, 4, 5)
+  }
+}