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
Visual Studio doesn't like LF line endings in solution files and always
converts them to CRLF when doing changes to the solution. Notably, this
affects the solutions in the release archive.
Closes https://github.com/curl/curl/pull/1746