formio: ir.asset (base model) to replace formio.version.asset

[bobslee]

Since Odoo v 15.0 there's a model ir.asset.
https://www.odoo.com/documentation/16.0/developer/reference/frontend/assets.html

Let's research whether ir.asset can replace the version asset model: formio.version.asset
Consider the asset files could be stored 2 ways:

• static: basically this means in the static directory of a module
• attachment: as ir.attachment record, which is a reference to the file in the Odoo filestore.

This should be taken into account (and refactored) for serving the assets to the DOM document.

If this suggestion will make it (to implement), also data migrations should be done, regarding the models to replace.

This change (migration) could be benificial in maintaining and upgrading the formio module.