Consider adding a storage.format() to erase and create a fresh filesystem #577
Description
It would be nice to be able to erase and re-create a damaged filesystem from the REPL or a program. Currently on non-Express boards we need to erase all of flash and then reload CircuitPython. On Express boards we have a special Arduino program that erases SPI flash, and then we need to reload CPy.
Something like storage.format(<filesystem>) would be helpful. One minor issue is how to specify the filesystem if it's so damaged we don't know what it's named.
Some previous discussion: #386 (comment) ff.