**Summary**
Pagination of HTML documents is currently unused. The `Page` class and
concept were deeply embedding in the legacy organization of HTML
partitioning code due to the legacy `Document` (= pages of elements)
domain model. Remove this concept from the code such that elements are
available directly from the partitioner.
**Additional Context**
- Pagination can be re-added later if we decide we want it again. A
re-implementation would be much simpler and much lower impact to the
structure of the code and introduce much less additional complexity,
similar to the approach we take in `partition_docx()`.
**Summary**
Remove use of `partition.common.document_to_element_list()` by
`HTMLDocument`. The transitive coupling with layout-inference through
this shared function have been the source of frustration and a drain on
engineering time and there's no compelling reason for the two to share
this code.
**Additional Context**
`partition_html()` uses `partition.common.document_to_element_list()` to
get finalized elements from `HTMLDocument` (pages). This gives rise to a
very nasty coupling between `DocumentLayout`, used by
`unstructured_inference`, and `HTMLDocument`.
`document_to_element_list()` has evolved to work for both callers, but
they share very few common characteristics with each other.
This coupling is bad news for us and also, importantly, for the
inference and page layout folks working on PDF and images.
Break that coupling so those inference-related functions can evolve
whatever way they need to without being dragged down by legacy
`HTMLDocument` connections.
The initial step is to extract a `document_to_element_list()` function
of our own, getting rid of the coordinates and other
`DocumentLayout`-related bits we don't need. As you'll see in the next
few PRs, all of this `document_to_element_list()` code will end up
either going away or being relocated closer to where it's used in
`HTMLDocument`.
**Summary**
Clean `tests_unstructured/partition/test_html.py` in preparation for
broader refactor of HTML partitioner to follow. That refactor will
address a cluster of bugs.
Temporarily remove blank lines in tests so reordering tests in following
commit is easier to follow. Those will go back in after that.
