Add images for common data filetypes

[josegonzalez]

Would be great to include creative commons logos for stuff like:

• csv
• excel
• parquet

These could be used for dataflows to show how data is being moved around a system :)

[mingrammer]

Good ideas :) We can make a new provider for this special types, data provider for example.

[mycaule]

There is already the icons from from diagrams.generic.database import SQL which you can derive easily.