refactor: introduce a shared folder for partials and images from both JS and Python courses (#1889)

#### Previously

- Python course had an `images` folder with images
- New JS course (unlisted) had an `images` folder as well, but it was
just a symlink to the Python one
- Each of the courses had it's own `_exercises.mdx`

#### After this change

- There will be three top level folders: `scraping_basics` with shared
stuff, `scraping_basics_javascript2` for the JS course,
`scraping_basics_python` for the Python course
- The `scraping_basics` contains shared images and partials (currently
just `_exercises.mdx`, but there is a potential to share more in the
future if we want)
- The JS and Python courses link to the shared folder for images and
partials
- Only one shared `_exercises.mdx`, no duplication
- No symlinks or other hacks

#### Note

This change doesn't touch the original `scraping_basics_javascript`
course at all.

Author: honzajavorek

.github/styles/config/vocabularies/Docs/accept.txt

@@ -119,7 +119,7 @@ subreddits?
 [Ss]ubwoofer
 Tripadvisor
 upvote
-walkthroughs?
+[Ww]alkthroughs?
 
 ul
 [Aa]gno