[FL-1443, FL-1289] Move assets compilation to separate Makefile. Add scripts folder. Add OTP flashing with DFU. (#531)

* Assets: move assets compilation to separate Makefile. Move all scripts to scripts folder. Add scripts ReadMe. Add precompiled assets.
* Split assets.py into separate entities. Option bytes for FL-1289 and checker/setter.
* Cli: explicitly initialize variable befor use in api_hal_vcp_rx_with_timeout
* Rename ob_check script to ob.

scripts/flash_otp_version_dfu.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+set -x -e
+
+if [ "$#" -ne 1 ]; then
+    echo "OTP file required"
+    exit
+fi
+
+if [ ! -f $1 ]; then
+    echo "Unable to open OTP file"
+    exit
+fi
+
+STM32_Programmer_CLI -c port=usb1 -d $1 0x1FFF7000
+
+STM32_Programmer_CLI -c port=usb1 -r8 0x1FFF7000 8