✨ 🎨 Allow foreach else inside of get helper

[ErisDS]

closes #7242

• before this, the get helper's else was used for empty resultsets
• the argument was made that we should fall through to a foreach or with helper's else instead
• I agree that this is the more natural, consistent approach, and so would like to change it for Ghost 1.0

E.g. as of this PR we now have:

{{#get "posts" filter="tag:doesnt-exist"}}
  {{#foreach posts}}
  {{else}}
    this gets executed because there are no results
  {{/foreach}}
{{/get}}

instead of

{{#get "posts" filter="tag:doesnt-exist"}}
  {{#foreach posts}}
  {{else}}
  {{/foreach}}
{{each}}
    this gets executed because there are no results
{{/get}}

[kirrg001]

works 👍