UI: allow side docks to be tall

before: widgets docked on the sides of the preview are of the height of
the preview

after: the user can toggle the setting in the docks menu so the side
widgets are of the height of the whole window

UI: change menu label to Full-height docks
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Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f