Switch back to `@oruga-ui/oruga` package name

[mlmoravek]

With the first release of Vue3, like many other libraries, we created an @oruga-ui/oruga-next package to support Vue3 as well as Vue2 with the main @oruga-ui/oruga package.

However, the separate @oruga-ui/oruga-next package was initially chosen to support Vue3 alongside the main Vue2 Oruga implementation.

When Vue2 was deprecated, we also deprecated our Oruga package for Vue2, @oruga-ui/oruga, and shifted our focus to Vue3, with the @oruga-ui/oruga-next package as the main package.

Now that it is almost a year since Vue2 was deprecated, I propose to change the package name back to @oruga-ui/oruga.

This can be done in two phases: First, we undeprecate the @oruga-ui/oruga package, and can release any further version under @oruga-ui/oruga-next as well as @oruga-ui/oruga, to have a smooth transition for everyone.
After that, we can deprecate the @oruga-ui/oruga-next package any time later.