Bring TinyBlazorAdmin code to this repo

[FBoucher]

I need to bring the website into this repo. Because major / breaking code changes will be I won't do a module.

I was thinking submodule.... But I think a copy would make it simpler. Because this project target beginner I think it will be easier.

The Blazor App code will go into /src/app (need to move code from the API #319)