Add clinical trials information

[nightsh]

Add data about the current clinical trials being conducted against COVID-19.

This might (or might not) involve scraping some clinical trials registries (e.g. EUCTR, ICTRP etc.).

I will self assign as I wanted to get them anyway, can't think of a better place to put them. The only caveat is that I will try to patch some of the OpenTrials collectors in order to do that and that might not be the straightest (or most obvious) path to extract that information.

[nightsh]

Oh, turns out I can't assign myself to it, I'll just post updates here when (if?) there's any progress from my side.

[anuveyatsu]

@nightsh hey, I guess the upstream repo is also going to include clinical trials (at least for US):

CSSEGISandData/COVID-19#1250