resolves issue #2016: workflow trigger for SO, PO, PRJ tables

Adds triggers to:
- `cohead`
- `pohead`
- `prj`
- (tohead and wo are added via https://github.com/xtuple/private-extensions/pull/529)
- `tohead`
- `wo`
which, `after` insert, all call the same function, `xt.createwf_after_insert()`. `xt.creatwf_after_insert()` gathers the correct parameters for the table and then calls `xt.workflow_inheritsource` to generate the "default" workflows. 

[Here's a problem](https://github.com/xtuple/xtuple/pull/2039/files#diff-1c69b7bf17bf3488bb7497f56f49d692R40): ... the pohead table does not link to Purchase Order Type, which breaks workflow generation outside of the web client. Purchase Order workflow should use Vendor Type for configure default workflows.

**UAT:**
To 'turn on' this generate default workflow functionality, run this sql script `select setmetric('TriggerWorkflow', 't')`. 
Prepare the "default" workflows for each workflow type:
- Setup > Sale Types > CUST > Add a workflow (the details/setup of the wf don't matter)
- Setup > Project Types > Standard > Add a workflow
- Setup > Purchase Types > Add a Purchase Type *NORMAL* > Add a workflow

1. Create a Sales Order, the Workflow panel should be populated with the default workflow, save. Open the Sales Order > Workflow > There should be a duplicate workflow.
2. Create a Purchase Order, the Workflow panel should be populated with the default workflow, save. Open the Purchase Order > Workflow > There should be a duplicate workflow.
3. Create a Project, the Workflow panel should be populated with the default workflow, save. Open the Project > Workflow > There should be a duplicate workflow.
This looks good by me.