Update indicators with NAN codes

[dshemetov]

This issue will track the production and the merging of the PRs that add bare bones NAN code support for individual indicators (enable deletions by tracking nan "val" entries and add codes for data ranges). Related work on the DB side here.

• [x] cdc_covidnet #914 not deployed, not published
• [x] change_hc #898
• [x] claims_hosp #902
• [x] combo_cases_and_deaths #944
• [x] covid_act_now #989
• [x] doctor_visits #990
• [x] ~google_health~
• [x] google_symptoms #993
• [x] hhs_facilities #1006
• [x] hhs_hosp #1008
• [x] jhu #839
• [x] nchs_mortality #1016
• [x] quidel #866
• [x] quidel_covidtest #999
• [x] safegraph #845 no longer supported
• [x] safegraph_patterns #859
• [x] usafacts #843

[dshemetov]

Only a partial fix there

[nmdefries]

@dshemetov Can we close this?

[dshemetov]

Still a bunch of indicator update PRs in the queue from almost 2 years ago. Might still be worth pushing them through at some point, though low priority.