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
... so that runtests can skip individual test cases that test features
that are explicitly disabled in this build. This new logic is intended
for disabled features that aren't otherwise easily visible through the
curl_version_info() or other API calls.
tests/server/disabled is a newly built executable that will output a
list of disabled features. Outputs nothing for a default build.
Closes#3950
