refactor: move Highlight to its own file

damus/Components/Highlight.swift

@@ -0,0 +1,39 @@
+//
+//  Highlight.swift
+//  damus
+//
+//  Created by William Casarin on 2023-01-23.
+//
+
+import Foundation
+import SwiftUI
+
+
+enum Highlight {
+    case none
+    case main
+    case reply
+    case custom(Color, Float)
+
+    var is_main: Bool {
+        if case .main = self {
+            return true
+        }
+        return false
+    }
+
+    var is_none: Bool {
+        if case .none = self {
+            return true
+        }
+        return false
+    }
+
+    var is_replied_to: Bool {
+        switch self {
+        case .reply: return true
+        default: return false
+        }
+    }
+}
+