[C++][FS][Azure] Rename `AzurePath` to `AzureLocation`

### Describe the enhancement requested

It's for readability.

See also the discussion about this: https://github.com/apache/arrow/pull/38708#discussion_r1395094715

We will also rename `AzurePath::path_to_file` to `AzureLoation::path`.

### Component(s)

C++