Fixes a crash of the builder script, `board.get("build.variant", None)` will throw an exception if the `build.variant` was not found (and not return `None` as the fallback value), but an empty string works, so check against that.
USB power defines moved directly into the board files, but still ensure that the macro always exists (with a default fallback value) to not fail the build.
Defines USBD_MAX_POWER_MA as a static 250mA, which is correct for all the boards supported in platform-raspberrypi (aka, RaspberryPi Pico and Nano RP2040 Connect)
* Add package.json
To make package easily integratable with PlatformIO
* Correct name back to original one
* Format package.json
* Add first shot at builder script
* Add USB stack flags, fix compile flags
* Formatting
* Add more link & USB flags
* Build Boot2 bootloader
* Formatting
* Generate linkerscript, linker fixes
* Fix linkflags, make firmware runnable
* Update USB flags and RAM size
* Correct USB flags, add dynamic sketch partitioning
* Restructure filesystem size and flash size logic into platform code
* Move C++ only flags to CXXFLAGS
* Add PlatformIO documentation
* Link to new platform.io document in the docs TOC
* Fix typos in platformio docs
* Fix one additional typo in platformio.rst
* Update docs
* Remove wrongly commited build folder
