speeds up the loading of third-party libraries

[FranckFreiburger]

Is your feature request related to a problem? Please describe.
Loading 3rd party libraries could be very long since vue3-sfc-loader is processing every dependencies through babel (for CJS transformation and dependencies static analysis).
For instance, babylon.max.js takes around 17s to load.

Describe the solution you'd like
The simplest solution is to give control to the caller about what to transpile and what to not transpile.
eg. do not transpile babylon

    const options = {
      ...
      async handleModule(type, getContentData, path, options) {

        if ( path.toString().endsWith('babylon.max.js') )
          return createCJSModule(type, await getContentData(false), options)

        return undefined;
      },
      ...

These libraries must be leaves of the whole dependency graph since no static analysis will be performed on them.
These libraries must already be CJS (or obviously UMD).

Additional context
see #50