Bump third_party/imgui/repo from 85395b7 to 1109de3 (#28201)

Bumps [third_party/imgui/repo](https://github.com/ocornut/imgui) from `85395b7` to `1109de3`.
- [Release notes](https://github.com/ocornut/imgui/releases)
- [Commits](ocornut/imgui@85395b7...1109de3)

---
updated-dependencies:
- dependency-name: third_party/imgui/repo
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>