As a consumer developer I can search a content by any custom field

• Type: Story
• Status: Closed
• Priority: Minor
• Resolution: Completed
• Affects Version/s: None
• Fix Version/s: Master
• Component/s: Headless Delivery API
• Labels:
  • Consider_For_7.3
  • fc_19_07
• Epic/Theme:
  • API_Content_Delivery
• Epic Link: headless-search-parameter
• Sprint: Headless-7.2-Nice to have

For the expando fields indexed as "text", add capabilities to search by the values of those fields