Add collection_permission for Content Entity template

[MaxPah]

Hello,
Looks like there is a permission needed for a content entity to access overview see https://www.drupal.org/node/2955178 in the entity the key is collection_permission:

[MaxPah]

Both pull request 3.x and 4.x created :

https://github.com/Chi-teck/drupal-code-generator/pull/212/files
https://github.com/Chi-teck/drupal-code-generator/pull/213/files