Adding LWP and IWP to default_spec.yml

[XiaSun-Atmos]

Adding LWP and IWP to default_spec.yml, with unit as g/m2.
This is tested on WFIP3 (WRF runs) UPP output. It should also work for HRRR.
Example plots as below:

[cshartsough]

Looks to be set up well. The high end of the range seems to be saturated, but I wouldn't be too worried about extending it unless you think users will notice and ask for it.

[cshartsough]

The lint test failed due to extra whitespace at the end of the new kg-to-g conversion. I hate those, but a quick fix, at least.

[XiaSun-Atmos]

Thanks @cshartsough !
The high end of the range does look saturated. The current colorbar range is per the users' (the local wfip team) request, so it should be good for a while;
Removed the extra whitespace at the end of the new kg-to-g conversion;
The last commit is to add lwp and iwp to wfip image lists.