Support readonly of property editors

[bjarnef]

Is your feature request related to a problem? Please describe.
Some time ago Umbraco implemented a feature in core whether property editors support readonly. E.g. i splitview etc where a boolean (toggle) is still rendered as a toggle, but disabled.
https://github.com/umbraco/Umbraco-CMS/blob/contrib/src/Umbraco.Web.UI.Client/src/views/propertyeditors/boolean/boolean.html#L13

https://github.com/umbraco/Umbraco-CMS/blob/d3b96a163feb031f8b33d63ab68098d65aa6686d/src/Umbraco.Web.UI.Client/src/common/directives/components/buttons/umbtoggle.directive.js#L118-L132

Describe the solution you'd like
Perhaps Umbraco Commerce can support this as well, when property editor supports it readonly?
Then we can still show a toggle for instance for an order property in cart and order, but it could be disabled on order for instance.

{
  "alias": "subscribeNewsletter",
  "label": "Subscribe to newsletter",
  "view": "boolean",
  "isReadOnly": true
},

The current isReadOnly property just render the label (readonly property ediitor I think). Of course if the property editor doesn't support readonly it will just have no impact.