3Delight output not respecting scalarformat value

[vNicolini]

Version: Gaffer-1.4.0.0b6-windows
Third-party tools: Arnold 7.2.5.1 / 3Delight 2.9.76

Description

Not sure if it's a user, driver or metadata error but it appears that when writing out EXRs from 3Delight it's not respecting the scalarformat plug value, being half in my case.
According to the EXR's metadata it is still saved as 32F but the file size (compared to an EXR from Arnold) makes me think other wise

Steps to reproduce

1. Create an output
2. Create a plug named scalarformat
3. Set the value of the scalarformat plug to half
4. Examine the EXR's metadata

See provided EXRs and repro scene attached

DBG-1010_Lighting_v0001.zip

[gkocov]

The output definition in NSI is split in two components - the outputdriver node and the outputlayer node. Currently when custom output parameters are added to a Gaffer Outputs node, they get exported only as outputdriver attributes. Since scalarformat is an outputlayer node attribute (as well as filter, filterwidth, etc.), unfortunately it can't be set from Gaffer at the moment.

The #5641 PR was created to address this very issue.