[instrument_builder] Improve error message specificity for file upload

[GeorgeMurad]

Brief Summary of Changes

• Improved error message handling for file uploads in Instrument Builder.
• Now provides specific error messages for:
  • Invalid extension. Only .linst files are allowed.
  • Spaces are not allowed in the file name.
  • Special characters are not allowed (only letters, numbers, and _).
  • Multiple periods in the file name are not allowed.
  • File name cannot end with a special character.

Testing Instructions

1. Try uploading different files with:

   • Valid names (validFile.linst) → Should succeed.
   • Names with spaces (my file.linst) → Should show "Spaces are not allowed."
   • Names with special characters (file@name.linst) → Should show "Special characters are not allowed."
   • Names with multiple periods (file.name.linst) → Should show "Multiple periods in the file name are not allowed."
   • Names ending with special characters (file_.linst) → Should show "File name cannot end with a special character."

2. Click "Load Instrument" after selecting a valid file → Should display a success message.

Additional Notes

• No changes were made to backend logic.

• This ensures better user experience and validation.

• Run:

npm run compile

Link(s) to related issue(s)

• [Instrument Builder] Error message for Upload of file could be more specific #8576