Add default community health files

[vplasencia]

Add default community health files such as CONTRIBUTING, CODE_OF_CONDUCT, Issue and pull request templates, etc.

The idea is to use all these files as defaults in all the repositories of the organization and create only in each repository, the files that we would like to adapt to that repository. This way, we can avoid creating the same files every time we create a new repository.

More information about it: https://docs.github.com/en/communities/setting-up-your-project-for-healthy-contributions/creating-a-default-community-health-file