fix: table HTML generation corrected

[pawel-kmiecik]

Currently unstructured-inference generates tables with missing markup:

<table>
  <thead> <!-- missing <tr> after <thead> -->
    <th>header cell1</th>
    <th>header cell2</th>
  </thead>
  <tr> <!-- would be nice to add <tbody> if <thead> is used -->
    <td>body cell1</td>
    <td>body cell2</td>
  <tr>
<table>

When it should look like:

<table>
  <thead>
    <tr>
      <th>header cell1</th>
      <th>header cell2</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>body cell1</td>
      <td>body cell2</td>
    <tr>
  </tbody>
<table>

Additionally, fixed fill_cells function which added redundant cells that break the HTML table layout when spanned cells were found.

[badGarnet]

we can just make this 0.7.35 for release