[Feature] ability to internalize only external urls or certain file types like zips

[pxpm]

In development mode, it would be very useful if we could internalize all the external files + zips for example. (external because they are external .. zips because they are resource consuming).

That would ensure that we could keep working on internal @bassetBlocks and/or internal .css/.js files without basset caching them, and we would be able to develop offline without reaching for external resources.

It can be two configs like: DEV_MODE_CACHE_EXTERNALS and DEV_MODE_CACHE_ZIPS.