Search autocomplete

[rosemcc]

New feature search autocomplete

When entering a search query the user is shown a dropdown list of search suggestions that they can select from. Autocomplete suggestions include all published page titles in the CMS as well as a manually-curated list of popular search terms that have been used in the past by ResearchHub users - derived from the Google Analytics Site Search data.

• Search autocomplete service stores the list of popular terms and performs a GraphQL query to load all page titles from Contentful
• The Search Bar component uses the autocomplete service to obtain the list of autocomplete terms
• It uses the Angular Material autocomplete component to render the autocomplete options
• The search bar component search input is changed to a reactive form so the user input can be observed as a stream
• The user input is used to filter the list of autocomplete terms to show only terms that match the input
• The input and autocomplete terms are lowercased, leading and trailing whitespace is removed and diacritic marks are ignored

[Trombach]

LGTM! I like how this is done with very little code. Just one suggestions that I added as a comment :)