Add calculation of table related metrics based on table_as_cells

[plutasnyy]

This pull request add metrics that are calculated based on table_as_cells instead of text_as_html. This change is required for comprehensive metrics calculation, as previously every colspan or rowspan predicted was considered to be an incorrect predicted (even if it was correct prediction)

This change has to be merged after https://github.com/Unstructured-IO/unstructured/pull/2892 which introduces table_as_cells field