Memory-x generation

[Iooon]

Add memory-x generation per chip.

• In parts.rs, each chip contains a vector of memory sections
• Make sure each chip has a FLASH and RAM section for cortex-m
• Separate SRAM banks to avoid undefined behaviour in case STOP/STANDBY modes are used (in the future)
  • We could have an option to combine them for now
• Generate the memory-x file per chip and add it to the respective directory in mspm0-metapac/src/chips