Migrate public ElectronHostHook code for Navigating event to a private place

[Daddoon]

Migrate public ElectronHostHook code for Navigating event to a private place.

It's mainly for maintenance. The ElectronHostHook code seen in index.ts / index.js, done for managing Navigating events must be:

• [ ] Migrated to a the BlazorMobile.ElectronNET assembly
• [ ] Injected at build time to the obj files of the user project
• [ ] Modyfing or Add the index.ts file on HostHook init, and register the method call.

If going this way, we will be obligated to create a new (again !) NuGet package like BlazorMobile.Build.ElectronNET.