Added descriptive FileNotFoundError handler for serial device connection

[tache]

• Added a detailed error message for FileNotFoundError when the serial device is not found.
• Included troubleshooting steps for common issues.

[CLAassistant]

All committers have signed the CLA.

[tache]

Existing:

Traceback (most recent call last):
  File "~/.pyenv/versions/3.12.2/bin/meshtastic", line 8, in <module>
    sys.exit(main())
             ^^^^^^
  File "~/.pyenv/versions/3.12.2/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/site-packages/meshtastic/__main__.py", line 1988, in main
    common()
  File "~/.pyenv/versions/3.12.2/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/site-packages/meshtastic/__main__.py", line 1242, in common
    client = meshtastic.serial_interface.SerialInterface(
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "~/.pyenv/versions/3.12.2/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/site-packages/meshtastic/serial_interface.py", line 52, in __init__
    with open(self.devPath, encoding="utf8") as f:
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
FileNotFoundError: [Errno 2] No such file or directory: '/dev/cu.SLAB_USBtoUART'

With update:

File Not Found Error:
  The serial device at '/dev/cu.SLAB_USBtoUART' was not found.
  Please check the following:
    1. Is the device connected properly?
    2. Is the correct serial port specified?
    3. Are the necessary drivers installed?
    4. Are you using a **power-only USB cable**? A power-only cable cannot transmit data.
       Ensure you are using a **data-capable USB cable**.

[ianmcorvidae]

Looks pretty good to me! Thanks for this.

[codecov]

Codecov Report

Attention: Patch coverage is 10.00000% with 9 lines in your changes missing coverage. Please review.

Project coverage is 60.22%. Comparing base (fc3b81d) to head (8c115dc).
Report is 8 commits behind head on master.

Files with missing lines	Patch %	Lines
meshtastic/__main__.py	10.00%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #735      +/-   ##
==========================================
- Coverage   60.35%   60.22%   -0.13%     
==========================================
  Files          24       24              
  Lines        3970     3980      +10     
==========================================
+ Hits         2396     2397       +1     
- Misses       1574     1583       +9     

Flag	Coverage Δ
unittests	60.22% <10.00%> (-0.13%)	⬇️

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