refactor(tui): remove unused revert diff parser (#39963)

Co-authored-by: Kit Langton <kit.langton@gmail.com>

packages/tui/test/util/revert-diff.test.ts

@@ -1,35 +0,0 @@
-import { describe, expect, test } from "bun:test"
-import { getRevertDiffFiles } from "../../src/util/revert-diff"
-
-describe("revert diff", () => {
-  test("prefers the actual file path over /dev/null for added and deleted files", () => {
-    const files = getRevertDiffFiles(`diff --git a/new.txt b/new.txt
-new file mode 100644
-index 0000000..3b18e51
---- /dev/null
-+++ b/new.txt
-@@ -0,0 +1 @@
-+new content
-diff --git a/old.txt b/old.txt
-deleted file mode 100644
-index 3b18e51..0000000
---- a/old.txt
-+++ /dev/null
-@@ -1 +0,0 @@
--old content
-`)
-
-    expect(files).toEqual([
-      {
-        filename: "new.txt",
-        additions: 1,
-        deletions: 0,
-      },
-      {
-        filename: "old.txt",
-        additions: 0,
-        deletions: 1,
-      },
-    ])
-  })
-})