fix(audio): Properly filter-out unavailable audio backends from UI

[bassdr]

No description provided.

[Malkierian]

What does this do that isn't already handled in LUS as it initializes mAvailableAudioBackends?

[bassdr]

You mean having the string on Lu's side? I can do that, I wanted to avoid depending on a pr in Lus for something as simple as that. I'll leave the pr here as is, while we see what LUS says.

[Malkierian]

No, I mean that GetAvailableAudioBackends returns mAvailableAudioBackends, which has already been filtered for availability.

[bassdr]

The list LUS gives us only has the enum, we have to provide a list of strings to dispa it in ImGui...

If we want to do that, we have to update LUS so it provides strings too, or I missed something, but I don't think so.

Here. I construct the map that imgui expects, based on the list LUS provides.

[Malkierian]

Ohhh, I didn't realize the strings weren't getting filtered. However, I'd prefer that the API name map be populated at startup like the renderer API name map is, rather than in the middle of a menu lambda. Unless someone can tell me why I thought calling UpdateWindowBackendObjects() in the WIDGET_VIDEO_BACKEND case was necessary.

[Malkierian]

In other words, mirror the way availableWindowBackendsMap is handled as closely as possible, and I'll sign off on it.

[bassdr]

Done, should be good to ship, I ran clang-format, compiled, tested, et al.