codespell: Add configuration and fix spelling

After seeing issue #20848 (closed) I created a configuration for codespell and fixed/disabled all messages.

For easier reviewing I separated the changes into separate commit based on where the change was made and if it was only a comment or not.

Included are about 50 changes for British->American spelling. If this is undesired I can revert them (I have a backup of the previous changeset). Most changes were behaviour->behavior, followed by cancelled->canceled.

This check could be integrated into CI to automatically check on MR.

Fixes: #20848 (closed)
Topic-rename: codespell