enable-resume (#3537)

Adding the ability to resume conversations.
we have one verb `resume`. 

Behavior:

`tui`:
`codex resume`: opens session picker
`codex resume --last`: continue last message
`codex resume <session id>`: continue conversation with `session id`

`exec`:
`codex resume --last`: continue last conversation
`codex resume <session id>`: continue conversation with `session id`

Implementation:
- I added a function to find the path in `~/.codex/sessions/` with a
`UUID`. This is helpful in resuming with session id.
- Added the above mentioned flags
- Added lots of testing

codex-rs/Cargo.lock

@@ -666,6 +666,7 @@ dependencies = [
  "bytes",
  "chrono",
  "codex-apply-patch",
+ "codex-file-search",
  "codex-mcp-client",
  "codex-protocol",
  "core_test_support",
@@ -733,6 +734,8 @@ dependencies = [
  "tokio",
  "tracing",
  "tracing-subscriber",
+ "uuid",
+ "walkdir",
  "wiremock",
 ]