test(angular): add test for slides

[paulstelzer]

Ion-Slides is not working in production build like mentioned in #17032 and #17033

This issue was not fixed by #17037

Fix for no is to remove sideEffects - better solution would be great :)

[adamduren]

@paulstelzer According to the webpack documentation this can affect the ability to tree shake. Is there any information on the effects this change had? Also if you know what specific files have side effects they can be listed individually as an array to sideEffects vs a boolean.

Documentation

[paulstelzer]

This is just a temporary fix until we find something else. If we add sideEffects again, the build will be broken and slides are not working. sideEffects was activated with rc1, so rc0 was without it and all betas, too

and yes, only slides had this sideEffects, so in future only this can be excluded. but as I said it's just a temporary fix to make Ionic work again