Add Threat Stack vendor account

[koenrh]

Adds the Threat Stack vendor account.

Icon is already present:

cloudmapper/web/style.json

Lines 586 to 596 in e99df11

	{
	"selector": "[type = \"Threatstack\"]",
	"css": {
	"background-opacity": 0,
	"background-image": "./icons/logos/threatstack.png",
	"background-fit": "contain",
	"background-clip": "none",
	"width": 150,
	"height": 100
	}
	},

[CLAassistant]

All committers have signed the CLA.

[0xdabbad00]

Thank you @koenrh !