This PR ensures that `arcade.core` does not show up anywhere in "user
space". This is crucial for helping developers understand what objects
are safe to use, and helps maintain a good developer experience.
Specific changes:
- `ToolAuthorizationContext` and `ToolContext` are now visible via
`arcade.sdk`
- `ToolCatalog` is now visible via `arcade.sdk`
- `Toolkit` is now visible via `arcade.sdk`
- `config` is now visible via `arcade.sdk.config`
```
authors = ["Arcade AI <dev@arcade-ai.com>"]
```
vs
```
authors = ["Arcade AI <dev@arcade-ai.com"]
```
There is also now a ``make`` command for ``make install-toolkits``
