Add github.repository_name property to github context

[igagis]

Describe the enhancement
There is already github.repository ('owner/name') and github.repository_owner (owner from 'owner/name') in the github context.

Add github.repository_name to the github context which would represent the name part of the 'owner/name'.

[nikola-jokic]

Hey @igagis,

Thank you for providing the feedback and suggesting this enhancement! We kindly ask you to redirect this feedback to the GitHub Community Support Forum which our team actively monitors and would be a better place to start a discussion for new feature requests in GitHub Actions.

This enhancement affects multiple components within the platform, and it is a better starting point to increase its visibility.

For more information on this policy, please read our contribution guidelines.

Since this enhancement impacts the platform more generally, I will close this issue now. But please, post your feedback to the Forum. It will help us to prioritize it and routing it to the correct team.