done on behalf of @Ladyada, this PR does:

Add Adafruit FunHouse and upcoming Adafruit Feather Esp32s2
Update Adafruit magtag and metro esp32s2 to have tinyuf2 as factory app
Also modify platform.txt as discussed in adafruit#2 + adafruit#3 + adafruit#4 to add support for
Board/variant partition.csv, bootloader.bin ( priority is user sketch > variant > build.parition/boot )
upload.extra_flags to optionally flash tinyuf2 as factory application
Remove duplicated parameter in running python script in linux and windows
Please review and let me know if you want any changes.

Notes: tinyuf2 is a uf2 bootloader for multiple platforms. For esp32s2, it is an factory app to perform uf2 firmware update.