Thm2isis not properly propagating cube attributes

[acpaquette]

ISIS version(s) affected: 4.3.0 (and likely much older)

Description
Thm2isis is not propagating cube attributes applied to the output cube.

How to reproduce
Take any Themis image, VIS or IR.

Run the following:
Thm2isis from=/Path/to/input/Themis.img to=/Path/to/output/cube.cub+16bit

The resulting output cube will have a Real bit type rather than a Signed Word bit type.

Possible Solution
It's likely that the cube needs to have it's output attributes parsed from the direct string in the TO parameter of the UI.

[jessemapel]

Closed by #4504