One location for Pulsar endpoint information

[mira-miracoli]

@mtangaro was asking me where to collect information about the pulsar endpoints.
I think a group_vars/pulsar_endpoints.yml file would be a good possibility to:

• collect all the information in one place
• directly use the yaml file for defining variables that can be re-used in templates like destinations.yml.j2 and job_conf.yml.j2
• implement a semi automated workflow for adding new Pulsar endpoints
• maybe even implement a gh workflow to create a overview on the ESG page