Implement resolution to itemsFeedAll method

[Simply007]

Motivation

Related to kontent-ai/gatsby-packages#97

From the 1st of February the /items endpoint is limited to 1000 (incl. linked items) as described in Kontent API changes.
After that date, queries resulting in more than 1K content items per language won't load more than that 1K items.

By using alternative endpoint items-feed respectively itemsFeedAll from JS SDK users would lose the ability to relive URLs as well as linked items + components (as described in the issue linked abouve).

Proposed solution

Implement resolution the same way as using the items method.

Additional context

Including the content.item value in URLSlug resolver:

module.exports = class Page extends ContentItem {
  constructor() {
    super({
      urlSlugResolver: (link, context) => {
        const entry = context.item // THIS ONE
        const [parentElement] = entry ? entry.parent_element.value : []

        return {
          url: `${parentElement ? `/${parentElement.url_slug.value}` : ``}/${
            entry.url_slug.value
          }`,
        }
      },
    })
  }
}

[Enngage]

fixed by 6e30485