Taxonomy term listings are broken in RTL

[klonos]

Description of the bug
See screenshots bellow...

Steps To Reproduce

1. Enable the Language core module

2. Add an RTL language (Arabic or Hebrew for example), and set that as the site default -> this should switch the site to RTL

3. If this is a fresh installation, navigate to /admin/structure/taxonomy/tags; if not a fresh installation, then create a new vocabulary:

   

4. Add a single term, and head back to the "List terms" tab -> the "Operations" header is misaligned, and the "Weight" header is shown (although the "Show row weights" link has not been clicked) 👎

   

5. Click the "Show row weights" link -> the drag handle is hidden 👍, but the weight selection dropdown menus are not shown in the weight column 👎 :

   

6. Add another term, and head back to the term listing page -> The "Operations" header is gone and the "Weight" header is shown instead 👎:

   

7. Click on "Show row weights" -> the row weight drop-down menus are shown, but under the "Operations" header 👎:

   

Expected behavior

• The "Operations" header is properly aligned with the respective column that holds the operations drop-buttons.
• The "Weight" header/column is hidden by default.
• The "Weight" header/column is shown when the "Show row weights" link is clicked, and hidden again when the "Hide row weights" link is clicked.

[klonos]

The mismatch between header and row columns is not an RTL-specific or CSS-related issue: #3869