Clean up optional dependency groups

[dstansby]

Fixes #2539.

[jhamman]

Thanks. Just one suggestion.

For groups with only one optional dependency, I think its best if we just use the dependency as the name.

[dstansby]

Is there any benefit in having a dependency group where the name is the same as the package? I'd suggest we either

• leave it as tree, to indicate "install this extra if you want to use tree()
• remove it altogether and just document that folks need to install rich to use tree()

[jhamman]

Is there any benefit in having a dependency group where the name is the same as the package? I'd suggest we either

• leave it as tree, to indicate "install this extra if you want to use tree()

If we do this, we should adopt the "feature-oriented groups" approach for the other groups as well. That would apply to fsspec for RemoteStore.

• remove it altogether and just document that folks need to install rich to use tree()

I favor this option actually for rich and universal-pathlib.

[dstansby]

pre-commit.ci autofix

[dstansby]

If we do this, we should adopt the "feature-oriented groups" approach for the other groups as well

👍 done. I also removed universal-pathlib, tree, and started a v3 what's new (I don't think this already exists?) to communicate what's changed from v2.