fix: Fix various cases of HTML text missing after partition (#1587)
Fix 4 cases of text missing after partition:
1. Text immediately after `<body>`
```html
<body>
missing1
<div>hello</div>
</body>
```
2. Text inside container and immediately after `<br/>`
```html
<div>hello<br/>missing2</div>
```
3. Text immediately after a text opening tag, if said tag contains
`<br/>`
```html
<p>missing3<br/>hello</p>
```
4. Text inside `<body>` if it is the only content (different cause from
case 1)
```html
<body>missing4</body>
```
Also fix problem causing
`test_unstructured/documents/test_html.py::test_exclude_tag_types` to
not work as intended.
This will close GitHub Issue#1543
unstructured
89bd2faa - fix: Fix various cases of HTML text missing after partition (#1587)
