Make the Measurement Dashboard Loading Indicator More Obvious

[gargshruti30]

When the user selects another value from the dropdown we can give a loader in the space where the graph is generated. It will look more prominent than now because the div showing "Updating Histograms"
was not visible to me as a first time user.
@chutten What do you think ?

[chutten]

I think the suitability of this will depend on how it looks and feels when it is in place. It might be worth a try, if you'd like to give it a go.

[gargshruti30]

@chutten I would like to do this as a part of my Outreachy internship during redesigning of measurements dashboard.

[chutten]

@gargshruti30 I have rewritten this a little to make it easier to find in our sea of Issues.