[Todo] Move feathericons.com into the Feathericons monorepo `feathericons/feather`

[colebemis]

Let's move the source code for feathericons.com into feathericons/feather.

Benefits:

• Pull requests on feathericons/feather will get deploy previews which is helpful for reviewing icons.
• feathericons.com will automattically get deployed when a new version of Feather is released so it will always be up-to-date.