feat: Adds stack separators, removes some unused nodes from cli-doc module

Sources/CliDocCore/Nodes/StackConfiguration.swift

@@ -0,0 +1,29 @@
+/// Represents the content of an ``HStack`` or a ``VStack``.
+///
+///
+public struct StackConfiguration {
+  public let content: [any TextNode]
+}
+
+@usableFromInline
+struct AnySeparatableStackNode<Separator: TextNode>: TextNode {
+
+  @usableFromInline
+  let content: [any TextNode]
+
+  @usableFromInline
+  let separator: Separator
+
+  @usableFromInline
+  init(content: StackConfiguration, separator: Separator) {
+    self.content = content.content
+    self.separator = separator
+  }
+
+  @usableFromInline
+  var body: some TextNode {
+    content.removingEmptys()
+      .map { $0.render() }
+      .joined(separator: separator.render())
+  }
+}