Cleanup u64 vs usize usage

There's a lot of place where we use usize where we shouldn't.

There is an initial cleanup that is done in https://github.com/lancedb/lance/pull/4080 as a part of upgrading the object_store version. But this only does changes up to the Lance reader which has functions like:

    /// Object/File Size.
    async fn size(&self) -> object_store::Result<usize>;

    /// Read a range of bytes from the object.
    ///
    /// TODO: change to read_at()?
    async fn get_range(&self, range: Range<usize>) -> object_store::Result<Bytes>;

Ideally we should propagate the usage of u64 to all callers to make sure we do not do redundant conversions. Create this issue to track this work.

Start by reviewing PR 4080 and the Lance reader APIs shown in the issue, especially size() and get_range(). Trace their callers to identify remaining usize usage and conversions. Done means u64 is propagated through the relevant callers without redundant conversions.