This commit automates the process of documenting the licenses of
Invidious Javascript files through a compile time macro in the
licenses.ecr template file.
This should hopefully help keep the license documentation up-to-date
and allow extensions like LibreJS to always be able to load the latest
Javascript files of Invidious.
Currently only Invidious's first-party Javascript files are supported.
In the future it should be possible to leverage videojs-dependencies.yml
to automatically document the Javascript licenses for
VideoJS and co. as well.
