Allow loading data from URL passed as URL parameter

[stijn-uva]

In which part of the interface would this feature applies?

• 1. Load your data
• 2. Choose a chart
• 3. Mapping
• 4. Customize
• 5. Export

Is your feature request related to a problem? Please describe.
I am one of the developers of 4CAT. Our tool is used by researchers and journalists to do social media data analysis. It can output a variety of analyses as CSV files, e.g. a file containing the amount of tweets per month in a dataset, and so on. Many of these can be visualised very well with RawGraphs and we often recommend people to do so. Right now this requires a manual step where people e.g. download the file and upload it into RawGraphs. We would like to be able to add a "visualise with RawGraphs" button to the interface which would open RawGraphs and open the data file 'automatically'.

Describe the solution you'd like
It is already possible to load data from a URL in the "load your data" step in RawGraphs. We can instruct people to use this, but it would be even easier to be able to pass the data file URL to RawGraphs via a URL parameter, e.g. https://app.rawgraphs.io/?datafile=[4CAT_url]. Then we - and other tools - could in fact offer such a 'visualise with RawGraphs' button.

Describe alternatives you've considered
This feature was added to v1 with PR #176 and there is an open issue for it in #140 but that one is also labeled for v1. Since RawGraphs v2 has come out, and does not seem to support this feature, I figured it would make sense to open a new issue.

Additional context
I'd normally just open a PR for this but unfortunately I am not familiar with React.

[sal-uva]

Bumping this, would be a very welcome feature!