ci: separate native builds into Android and iOS

[OS-pedrogustavobilro]

To be in accordance to other capacitor plugin repositories we have.

[jcesarmobile]

I don't think building the plugin and the example app is needed here, build-example-app needs verify-plugin, which needs build-packages, which builds the plugin and both example apps, so they should be built at this point.

And BTW, should we sync/build the example-app-spm too?
I don't think we are doing it in other plugins which has two example apps, but what's the point of having the spm variant if we are not doing anything with it?

[OS-pedrogustavobilro]

Accidentally didn't reply in thread, refer to my reply on #129 (comment)

[OS-pedrogustavobilro]

Regarding the plugin build being necessary, yes it's already being applied in the build-packages job, but the dist folder goes away when switching to another (in this case build-example-app) step.

It is possible that the native build passes without the web build, to me it logically makes sense to stay, while still making sense to have the build step separate before so that we can get earlier feedback if web build fails.

As for the example-app-spm native build, you are right, I'll add that step here and to other repos that have it.

We only added example-app-spm to some repositories when we were testing SPM compatibility on plugins that didn't have it (this was one of them). One day we'll only have one example app with SPM, but for now it still makes sense to keep CocoaPods variant imo.