[Feature]: Is it possible to build termux-app with pacman as the default package manager?

### Feature description

I have successfully built bootstraps.zip using the pacman option, but now having installed that in my build of termux-app, I get the following error when trying to install apps:
```
/data/data/com.termux/files/usr/bin/pkg: line 348: pacman: command not found
```

Or do I just need to include pacman in the bootstraps.zip build?

### Additional information

N/A