object_store documentation is broken

[alamb]

Describe the bug
I was trying to render the docs while working on #4682 and I hit an error

error: unresolved link to `ObjectStore::copy_if_not_exists`
  --> src/aws/copy.rs:20:32
   |
20 | /// Configure how to provide [`ObjectStore::copy_if_not_exists`] for [`AmazonS3`]
   |                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no item named `ObjectStore` in scope
   |
note: the lint level is defined here
  --> src/lib.rs:18:9
   |
18 | #![deny(rustdoc::broken_intra_doc_links, rustdoc::bare_urls, rust_2018_idioms)]
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: unresolved link to `AmazonS3`
  --> src/aws/copy.rs:20:72
   |
20 | /// Configure how to provide [`ObjectStore::copy_if_not_exists`] for [`AmazonS3`]
   |                                                                        ^^^^^^^^ no item named `AmazonS3` in scope
   |
   = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`

error: unresolved link to `ObjectStore::copy_if_not_exists`
  --> src/aws/copy.rs:27:19
   |
27 |     /// If set, [`ObjectStore::copy_if_not_exists`] will perform a normal copy operation
   |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no item named `ObjectStore` in scope

This appears to have been added in #4239 but I couldn't find any CI jobs that check the object_store docs

To Reproduce

cd object_store
cargo doc --all-features

Expected behavior
Docs should build cleanly, and that should be verified by CI

Additional context

[tustvold]

This is intentional, docs.rs is built with all features - https://github.com/apache/arrow-rs/blob/master/object_store/Cargo.toml#L30

Conditionally compiling links based on feature flags is pretty grim, you end up writing things like https://github.com/apache/arrow-rs/pull/1134/files#diff-73978efa44253b6c1cafc48e0fd042b761ebfff35cb32c9f53717d1641dab0feR23

[alamb]

This is intentional, docs.rs is built with all features - https://github.com/apache/arrow-rs/blob/master/object_store/Cargo.toml#L30

I ran cargo doc --all-features and it still failed 🤔

[tustvold]

Oh... In that case this must be fallout from splitting object_store into its own workspace 👍

[tustvold]

label_issue.py automatically added labels {'object-store'} from #4684