Create Big4.gd for Godot 4.0

[ynot01]

Changes in new file for GD4:

• TYPE_REAL changed to TYPE_FLOAT
• stepify changed to snapped
• toFloat function was changed to return snapped(float(mantissa*pow(10.0, exponent)),0.01) instead of stepify(float(str(mantissa) + "e" + str(exponent)),0.01) as Godot 4 has no float(String) float constructor
• const other changed to var other because GD4 will not let you change a const dictionary
  • Static functions that utilized other changed to be not static because static functions cannot access instance variables
• Added @warning_ignore as # warning-ignore is deprecated