Split resources

[gabriel-tessier]

Here one improvement I thought about, and it's also several time listed in the diagrams issues.

• Split the resources and add the providers as dependencies, as usually nobody work on all provides at the same time. I think generic and programming providers should stay in the main project and all the others should be installed separately and have their own version. This one will also help the diagrams-web (that I only use) to be more clear as it will only display the providers installed. Also other merit is that one person can be assigned to curate a provider, it should be as simple as add or remove icons files.
  There a big work to do on the code to be able to do it and it will certainly broke a lot of things, I think that if there's this change, version can be decoupled from diagrams and follow it own versioning.

The issue about:
mingrammer/diagrams#764