feat: support `nonamespace` for scratch org creation

[attilah]

Describe the feature Extend the config schema for scratch org pools to support the nonamespace argument for org creation.

[azlam-abdulsalam]

Cool, never know it existed

For context

sfdx force:org:create -f project-scratch-def.json --nonamespace as detailed in

https://developer.salesforce.com/docs/atlas.en-us.sfdx_dev.meta/sfdx_dev/sfdx_dev_scratch_orgs_create.htm