feat: Working on node builder

Sources/CliDoc/Modifiers/AnyModifier.swift

@@ -0,0 +1,14 @@
+public struct AnyNodeModifier: NodeModifier {
+  @usableFromInline
+  let modifier: any NodeModifier
+
+  @inlinable
+  public init<N: NodeModifier>(_ modifier: N) {
+    self.modifier = modifier
+  }
+
+  @inlinable
+  public func render(_ node: any NodeRepresentable) -> any NodeRepresentable {
+    modifier.render(node)
+  }
+}