[FEATURE] #97667 - Add keyboard support for Multiselect

[brotkrueml]

As this manual is for editors, the different types are explained by screenshots where the keyboard commands can be used.

Additionally, a TOC has been added.

Resolves: TYPO3-Documentation/Changelog-To-Doc#412
Releases: main, 12.4

[garvinhicking]

(Not fully reviewed yet, out of time)

[github-actions]

The backport to 12.4 failed:

The process '/usr/bin/git' failed with exit code 1

stderr

error: could not apply 7c4a18b... [FEATURE] #97667 - Add keyboard support for Multiselect
hint: After resolving the conflicts, mark them with
hint: "git add/rm <pathspec>", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".

stdout

CONFLICT (modify/delete): Documentation/Localization.ru_RU/HelpInside/KeyboardCommands/Index.rst deleted in HEAD and modified in 7c4a18b ([FEATURE] #97667 - Add keyboard support for Multiselect).  Version 7c4a18b ([FEATURE] #97667 - Add keyboard support for Multiselect) of Documentation/Localization.ru_RU/HelpInside/KeyboardCommands/Index.rst left in tree.

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-12.4 12.4
# Navigate to the new working tree
cd .worktrees/backport-12.4
# Create a new branch
git switch --create backport-162-to-12.4
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick 7c4a18b10c097ff7f1a4cf8f404dc7787732747b,433df796697fd12f1ca4edb7eb8e666116159238,f9631a052eb3deddeb3ce48a125971f51f4ca7a9
# Push it to GitHub
git push --set-upstream origin backport-162-to-12.4
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-12.4

Then, create a pull request where the base branch is 12.4 and the compare/head branch is backport-162-to-12.4.