Chores: Refactor approval Patch UI. Stack: [1/2] (#2049)

- Moved the logic for the apply patch in its own file

Stack:
#2050
-> #2049

codex-rs/tui/src/lib.rs

@@ -31,6 +31,7 @@ mod citation_regex;
 mod cli;
 mod colors;
 pub mod custom_terminal;
+mod diff_render;
 mod exec_command;
 mod file_search;
 mod get_git_diff;