feat: Adds vertical and horizontal separators, renames modifier protocol.

Sources/CliDocCore/Nodes/Separator.swift

@@ -0,0 +1,66 @@
+public enum Separator {
+
+  /// Represents a horizontal separator that can be used between text nodes, typically inside
+  /// an ``HStack``
+  public enum Horizontal: TextNode {
+    /// Separate nodes by spaces of the given count.
+    case space(count: Int = 1)
+
+    /// Separate nodes by tabs of the given count.
+    case tab(count: Int = 1)
+
+    /// Separate nodes by the provided string of the given count.
+    case custom(String, count: Int = 1)
+
+    @TextBuilder
+    @inlinable
+    public var body: some TextNode {
+      switch self {
+      case let .tab(count: count):
+        seperator("\t", count: count)
+      case let .space(count: count):
+        seperator(" ", count: count)
+      case let .custom(string, count: count):
+        seperator(string, count: count)
+      }
+    }
+  }
+
+  /// Represents a vertical separator that can be used between text nodes, typically inside
+  /// a ``VStack``
+  public enum Vertical: TextNode {
+    case newLine(count: Int = 1)
+    case custom(String, count: Int = 1)
+
+    @TextBuilder
+    @inlinable
+    public var body: some TextNode {
+      switch self {
+      case let .newLine(count: count):
+        seperator("\n", count: count)
+      case let .custom(string, count: count):
+        seperator(string, count: count)
+      }
+    }
+  }
+
+}
+
+@usableFromInline
+func ensuredCount(_ count: Int) -> Int {
+  guard count >= 1 else { return 1 }
+  return count
+}
+
+@usableFromInline
+func seperator(_ separator: String, count: Int) -> some TextNode {
+  let count = ensuredCount(count)
+
+  assert(count >= 1, "Invalid count while creating a separator")
+
+  var output = ""
+  for _ in 1 ... count {
+    output += separator
+  }
+  return output
+}