[Feature](lance) Expand file TVF path and multi-dataset support

## Parent

Tracked by #66340. The baseline s3() and local() Lance TVFs were introduced by #65730.

## Scope

- [ ] Expand glob patterns to multiple Lance datasets.
- [ ] Read multiple Lance datasets in one TVF invocation.
- [ ] Support additional file TVF entry points and broader path handling.
- [ ] Preserve dataset boundaries, version pinning, schema compatibility, and secure path handling.

## Completion criteria

- [ ] FE split planning and BE execution support every selected dataset.
- [ ] Tests cover glob expansion, mixed paths, multiple datasets, and incompatible schemas.
- [ ] User documentation describes supported TVFs, paths, and limitations.
- [ ] Representative local and object-storage paths are verified.

Start with the existing s3() and local() Lance TVFs introduced by #65730, then review the parent issue #66340. Trace FE split planning and BE execution for multiple datasets, and identify tests for glob expansion, mixed paths, schema compatibility, and local or object-storage paths. Done includes passing coverage and updated user documentation.

Written by the indexing model from the issue text.