Add licensing and copyright information for all files in this repository. This
either happens in the file itself as a comment header or in the file
`.reuse/dep5`.
This commit also adds a Github workflow to check pull requests and adapts
copyright.pl to the changes.
Closes#8869
- avoid writing "set ..." or "enable/disable ..." or "specify ..."
*All* options for curl_easy_setopt() are about setting or enabling
things and most of the existing options didn't use that way of
description.
- start with lowercase letter, unless abbreviation. For consistency.
- Some additional touch-ups
Closes#7688
