feat: [1/N] Add write-through cache for manifest list

[dentiny]

Which issue does this PR close?

• Closes https://github.com/apache/iceberg-rust/pull/1698

What changes are included in this PR?

Context: I see huge CPU time spent on manifest list loading, especially avro deserialization (see attached PR for details), I want to leverage the object cache to avoid unnecessary IO and deser.

Discussed online with @liurenjie1024 for a bit, see

• https://github.com/apache/iceberg-rust/pull/1698#issuecomment-3332906860
• https://github.com/apache/iceberg-rust/pull/512#discussion_r2365940293

we lean towards the path that:

• Make object cache a read-through and write-through cache for manifest and manifest list
• Later loading attempts from object cache first, could be either a read-through cache, or look-aside for easier implementation
• Make object cache internal and transparent, instead of allow external application to directly access

I plan to structure and split the series of PRs as follows:

• [x] Store manifest list into object cache, if cache enabled
• [ ] Load manifest list with object cache considered, which makes object store a part of file io
• [ ] Replicate the same procedure to manifest files

This PR finishes the first part, which also benefits existing cached scan.

Are these changes tested?

Yes, unit test added.