WIP: Initial implementation of the flash module

- Interface is mostly copied and adapted from the F4-HAL
- Hardfaults while programming flash

Author: JanekGraff

Cargo.toml

@@ -39,6 +39,7 @@ nb = "1"
 void = { version = "1.0", default-features = false }
 stm32-usbd = { version = "0.6", optional = true }
 bxcan = "0.6.0"
+embedded-storage = "0.3.0"
 
 [dev-dependencies]
 cortex-m-rt = "0.7"