Actions: logical `type` option for templates to make view decisions from

[loppear]

Motivated by letting templates decide what icon/displayClass to use rather than the register/controller determining this at creation.

Since the actions templates are global to an app (and so in theory shared for both admin and other uses), it's probably a good idea to namespace types (as we currently suggest for model names with module_type), or to also add a module option for the template to differentiate.

cc @davidkellerman

[loppear]

Another option is to use more granular cascading template names, following nxus/templater#21 so that apps can override the implementation at more than a global level.

(This might replace the template/templateMinimal override options at action add too, the current only uses of those options is to specify different behavior e.g. use POST, which should probably be an option rather than by overriding template.)

Actions would register template names for each action type as it is added, e.g. assuming we add module, type, and method options:

  actions.add(this.templatePrefix+'-list', "Delete", '/delete, {
    module: 'admin',
    type: 'delete',
    method: 'post'
  })

  // this is I think the best way we have of expressing template aliases, which maybe we should.
  let aliasTemplates = (name, alias) => templater.default().templateFunction(name,
    (_, args) => return templater.render(alias, args))

  let defaultTemplate = `actions-button-${options.method}`
  let moduleTemplate = `actions-button-${options.module}-${options.method}`

  options.template = `actions-${options.module}-${options.type}-${options.method}`
  aliasTemplates(moduleTemplate, defaultTemplate)
  aliasTemplates(options.template, moduleTemplate)
  // mutatis mutandis for templateMinimal

And now modules can replace the template for either a specific action, for a module, or globally.

  templater.replace().template('actions-button-admin-delete-post`, path)
  // or 
  templater.replace().template('actions-button-admin-post`, path)
  // or 
  templater.replace().template('actions-button-post`, path)

As well as having module and type available to do conditional view decisions within the template.