Change type on old flags that were using `choices` to use `flags`

[ozxybox]

Strata Hammer allows for custom flags pages, which is far more useful than choices for bitflags. Lots of old stuff still uses this old format! SCell added this feature a long time ago.

Before:

After:

[vrad-exe]

Oh it adds a new tab, I guess that's one way to do this. I was going to suggest having it display the list of flag check boxes as a keyvalue, didn't realize this feature was already implemented (seriously, why was this never announced in any capacity?)

[ozxybox]

I think this feature was from SCell’s old project, but I’m not certain. It’s a very old feature