Fix flash tests

[NikhitaR-IFX]

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Description

• Fixed large file transfer issue in internal flash --> psoc6_flash.c
• Refactored error messages in psoc_flash.c.
• It is hard to add VFS type to be displayed but atleast in IDE's will now clearly indicate if internal or external flash is used and the type (shown in attached ss)
  
• Enabled flash tests for BLE board (running on internal flash)
• Cleaned run_psoc6_tests.sh and create fs.py to perform dut test on fs separately.

[github-actions]

Code size report:

   bare-arm:    +0 +0.000% 
minimal x86:    +0 +0.000% 
   unix x64:    +0 +0.000% standard
      stm32:   +48 +0.012% PYBV10
     mimxrt:   +52 +0.014% TEENSY40
        rp2:   +56 +0.017% RPI_PICO
       samd:   +48 +0.018% ADAFRUIT_ITSYBITSY_M4_EXPRESS