Feature request : add account number

[DS-INRAE]

Overview of the Feature Request
It would be great to also have in the metrics a graph with the number of accounts.

Note: In the future, a pie chart of the different account types distribution could also be nice but would need to be discussed.

What inspired the request?
It is often asked by the project governance and a nice way to assess the growth of the installations.

Any open or closed issues related to this feature request?
IQSS/dataverse-metrics#32 already proposed adding account numbers

Community involvement
If not deemed irrelevant by the community or done before, INRAE will do it early 2024.

[DS-INRAE]

As the API part has now been merged, we will start working on adding this graph either in April or if not possible in May.

[DS-INRAE]

Added an (oversized) image, we (the Recherche Data Gouv team) still plan to make a PR for this addition in the following months :)