chore: adding 'Load this SAE' popup to docs table

[chanind]

Description

I've noticed users sometimes get confused on the pretrained SAE table docs page about how to load a specific SAE in their code. This PR adds a "Load this SAE" link to each SAE in the pretrained SAEs table in docs. Clicking this link will pop up the code to load the specific SAE in SAELens, with a "Copy code" button to make it easy to copy into your own work.

The JS/CSS is a bit hacky but should do the job.

Type of change

Please delete options that are not relevant.

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [x] This change requires a documentation update

Checklist:

• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] I have not rewritten tests relating to key interfaces which would affect backward compatibility

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 66.14%. Comparing base (8e09458) to head (3e9fb62). Report is 3 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #362 +/- ## ======================================= Coverage 66.14% 66.14% ======================================= Files 25 25 Lines 3373 3373 Branches 432 432 ======================================= Hits 2231 2231 Misses 1021 1021 Partials 121 121 ```

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[chanind]

discussed / approved offline