feat: add offset option to stm32CubeProg upload method

[fpistm]

Linked to stm32duino/Arduino_Tools#90

Thanks this PR, it is now possible to flash at specific offset using STM32CubeProgrammer upload method.
Then start at the specified address.

Using boards.local.txt feature:
https://arduino.github.io/arduino-cli/latest/platform-specification/#boardslocaltxt

For example to flash at 0x08002000 the Generic STM32F103C8T, define the offset like this:
GenF1.menu.pnum.GENERIC_F103C8TX.build.flash_offset=0x2000

Then,

stm32CubeProg.sh 0 Blink.ino.bin 0x2000 -g
      -------------------------------------------------------------------
                       STM32CubeProgrammer v2.13.0                  
      -------------------------------------------------------------------

ST-LINK SN  : 0023003E3137510539383538
ST-LINK FW  : V3J10M3B5S1
Board       : STLINK-V3SET
Voltage     : 0.00V
SWD freq    : 8000 KHz
Connect mode: Under Reset
Reset mode  : Hardware reset
Device ID   : 0x410
Revision ID : Rev X
Device name : STM32F101/F102/F103 Medium-density
Flash size  : 64 KBytes
Device type : MCU
Device CPU  : Cortex-M3
BL Version  : --



Memory Programming ...
Opening and parsing file: Blink.ino.bin
  File          : Blink.ino.bin
  Size          : 23.30 KB 
  Address       : 0x08002000 


Erasing memory corresponding to segment 0:
Erasing internal memory sectors [8 31]
Download in Progress:


File download complete
Time elapsed during download operation: 00:00:01.408

RUNNING Program ... 
  Address:      : 0x8002000
Application is running, Please Hold on...
Start operation achieved successfully