[Feature] Add key->filename system table and support batch/streaming read

### Search before asking

- [x] I searched in the [issues](https://github.com/apache/paimon/issues) and found nothing similar.

### Motivation

As the title, subtask of #7284

### Solution

_No response_

### Anything else?

_No response_

### Are you willing to submit a PR?

- [ ] I'm willing to submit a PR!

Start by reading the parent issue #7284, since this issue provides no files, tests, or implementation details. Define the scope for a key-to-filename system table and determine how batch and streaming reads should use it; done means both read modes support the new table as agreed in the parent issue.

Written by the indexing model from the issue text.