Allow customizing the remoteEntry.mjs file name

[gibsonjoshua55]

Most other aspects of builds are customizable through either the executor options or webpack config. This file name, however is difficult to adjust. Because it is set statically in the instantiation of the ModuleFederationPlugin in the withModuleFederation function, even wrapping that function doesn't easily allow that filename to be changed.

It would be great if we could set that filename in the ModuleFederationConfig options that we pass into that function. That way if a particular project needs that file renamed, we can do so without an additional build steps or overriding configurations.