obs4MIPs support

[lee1043]

Is your feature request related to a problem? Please describe.
I was wondering if intake-esgf can support obs4MIPs data products.

Describe the solution you'd like

from intake_esgf import ESGFCatalog
cat = ESGFCatalog().search(
    project_id=["obs4MIPs"]
    variable_id=["tas", "pr"],
)

Describe alternatives you've considered
This was my practice from a while ago to generate local obs4MIPs catalogue JSON file, which I used directory tree structure to retrieve facets.