arrow

GH-40562: [C++] Repair FileSystem merge error (#40564)



### Rationale for this change

Failure to rebase and build when merging https://github.com/apache/arrow/pull/39067 (which renamed `internal::Uri` -> `util::Uri`) led to a merge conflict since https://github.com/apache/arrow/pull/40325 added more usages of `internal::Uri`

### What changes are included in this PR?
Rename internal::Uri -> util::Uri

### Are these changes tested?
Yes

### Are there any user-facing changes?
No

* GitHub Issue: #40562

Authored-by: Benjamin Kietzman <bengilgit@gmail.com>
Signed-off-by: Benjamin Kietzman <bengilgit@gmail.com>