Chore: hoist example projects for discoverability

[jkelleyrtp]

Hoist all of our example projects into a top-level "example-projects" folder, similar to NextJS and Leptos.

This should make discoverability easier.

Also removes the OIDC example since it wasn't working and wasn't properly updated for 0.5.

Cut out of #2779 to make that PR smaller

Closes DioxusLabs/example-projects#45

[ealmloff]

I like these examples being at the top level, but the /examples vs /example-projects distinction doesn't seem that useful. Many of these examples are simple unstyled examples that happen to use a full project to make the cargo.toml easier to copy. It might be better to just keep the example-projects we moved over from the original repo in the folder and fullstack-hackernews and move the rest of the full crate examples into the examples folder