Displaying of just model or obs data should bypass collocation entirely

[lewisblake]

Is your feature request related to a problem? Please describe.
When we want to look at obs-only or model-only data, we have to hack the code to create fake model data. Fake obs data is not yet implemented but being discussed. Ideally, this would never be needed as the code should be able to bypass colocation entirely in these cases. The ColdataToJsonEngine could be made more robust, or we could implement an analogous DataToJsonEngine which handles just the data read in. This would make processes much faster in these cases.

Describe the solution you would like to see
Above

• Would you be able to work on this solution yourself? No
• How can the Pyaerocom development team assist you? PRs, discussions