[conan-center] Validate license with the provided one on Github

[uilianries]

The Github API offers a way to detect the license listed on the repository: https://docs.github.com/en/rest/reference/licenses

We could detect it when available, and compare to the license attribute.

So far, we have been doing manually when reviewing recipes.

It won't achieve 100% of PRs, because not all projects offer a license file or are not hosted on Github, but it improve our review time.

[uilianries]

Gitlab also offers same https://docs.gitlab.com/ee/api/license.html We can do it on separated PRs.