Haldex bugfixes & General Housekeeping

[ConnorHowell]

I can probably split this up into seperate PR's if it's easier.

Summary of changes

• Removed ESP flashing related utilities
• Removed BLE (UART & J2534 only now)
• Fixed pillow dep for GH Actions building (32 bit wheels were dropped and building from source wasn't working; resorted to prebuilt only) (https://github.com/python-pillow/Pillow/issues/6941)
• Corrected Haldex checksumming (correct checksums were generated.... just not applied to the binary before flashing!!)
• Implemented support for varying length Haldex calibrations. (This may be considered kinda hacky; the block length is at offset 0x14 from the start of the CAL so it's pulled from there for blocks_from_bin. To correct the length used for RequestDownload the block length is set to the length of the binary in haldex_flash_utils.py

[bri3d]

LGTM. Next time we make a real release we'll have to do a writeup about the new J2534 stuff as well as try to get Switchleg to provide Linux+OSX binaries for it.