Back Side Placement Angles Are Incorrect When Using the Gerber (experimental) Option

Description

When generating placement files using the Gerber (experimental) option, the rotation angle of components mounted on the back side of the board are 180 degrees off from where they should be. Attached is the relevant portion of The Gerber Layer Format Specification - Revision 2022.02:

Steps to reproduce

1. Place a component on the back side of a design and rotate it as shown in the lower right of the image above (note that in KiCad, this component is at a rotation angle of -170 degrees but in Gerber it is at +10 degrees)
2. Select File->Fabrication Outputs->Component Placement (.pos) and select the Gerber (experimental) option. Then click Generate Position File.
3. Open the resulting Gerber file with a text editor and find the placement information for the component - it will look something like this:

 %TO.C,"U4"*%
 %TO.CFtp,"Diodes_SOT-553"*%
 %TO.CVal,"Diodes_SOT-553"*%
 %TO.CLbN,"Package_TO_SOT_SMD"*%
 %TO.CMnt,SMD*%
 %TO.CRot,-170*%

4. Note that the .CRot attribute has a value of -170 when it should be 10.

KiCad Version

Version: (6.0.5), release build

Libraries:
	wxWidgets 3.1.5
	libcurl/7.82.0-DEV Schannel zlib/1.2.12

Platform: Windows 10 (build 19043), 64-bit edition, 64 bit, Little endian, wxMSW

Build Info:
	Date: May  3 2022 00:36:16
	wxWidgets: 3.1.5 (wchar_t,wx containers)
	Boost: 1.79.0
	OCC: 7.6.0
	Curl: 7.82.0-DEV
	ngspice: 36
	Compiler: Visual C++ 1929 without C++ ABI

Build settings:
	KICAD_USE_OCC=ON
	KICAD_SPICE=ON