Before this commit, the exports field of `@theatre/r3f` was:
```
"exports": {
".": "./dist/index.js",
"./extension": "./dist/extension/index.js"
},
```
So users could import the extension from '@theatre/r3f/extension'
However, if the user’s bundler doesn’t support the exports field, they’d have to import from @theatre/r3f/dist/extension. There are 3 problems with this approach:
1. We have to ask users to try both paths and see which works for their bundler.
2. Users can’t copy code from each other if their bundler setups are different.
3. To make matters worse, if a user’s bundler supports exports, they can’t import from @theatre/r3f/dist/extension.
This is all confusing, so we're fixing it by exposing @theatrer/3f/dist/extension and not @theatre/r3f/extension. Uglier, but more consistent, and avoids the above 3 problems.
