Support arm32 export on Android

Specifically I'm trying to target the Kindle Fire Kids tablet, working on a little game for my pre-school son.

It's straightforward enough to support it, as I managed to do it in a fork just by changing the scons flag for the architecture:
https://github.com/godotjs/GodotJS/commit/7031bfbbd8d43494b39741ffca00ad76472f8848

The build works well enough. However we want an export template that supports *both* architectures, so scons must be run twice with the different sets of flags. (This was easier on the old build system as there were already two scons runs to support x86 as well.)

I would have submitted a PR for this but I wasn't immediately sure how best to do this in github actions; ideally there'd be a matrix for architectures but I don't think a matrix can be used here? Perhaps a comma-separated list of architectures and run scons in a loop...?