Change ListBoxHeader/Footer to Begin/EndListBox for imgui 1.89.6

[Mokona]

imgui 1.89.6 removed the ListBoxHeader and ListBoxFooter functions.

[floooh]

Thanks for the PR! I'll need to sync the merge with updating the fips-imgui dependencies here though, so I can't merge immediately:

https://github.com/fips-libs/fips-imgui

[Mokona]

I checked the time of addition of BeginListBox(). This new function has been added in March 2021 for version 1.81.

The existence of previous function ListBoxHeader() was kept for easy deprecation change.

I've cloned a new depot with chips and chips-test and this PR change, without touching the references fips-imgui, and it seems to work, unless I missed a step (my test was not pushed more than that though, I'd stay cautious).

[floooh]

Ah right... thanks for the info :) In that case I guess I can merge (I'll wait for the CI pipeline to finish)

[floooh]

...and merged, many thanks!

(I wonder why I haven't started the CI checks yesterday, because then it would be obvious that it works with Dear ImGui 1.89.5 :)