Add `title` chip

[paperboyo]

What does this change?

Adds a chip for easier searches for title.

How should a reviewer test this change?

Press + and notice title in the dropdown. Type title followed by a colon and notice it turning into a chip. I haven’t added it to Advanced search flyout, coz self-explanatory and the flyout is too long already.

Just a note that adding it to QuerySyntax.scala seems superfluous as @andrew-nowak notes “https://github.com/guardian/grid/pull/3132 made AllowedFieldName pretty pointless”. But added for cleanliness.

How can success be measured?

@honorcb is happy.

Who should look at this?

@guardian/digital-cms

Tested? Documented?

• [x] locally by committer
• [ ] locally by Guardian reviewer
• [ ] on the Guardian's TEST environment
• [ ] relevant documentation added or amended (if needed)

[prout-bot]

Seen on auth, usage, image-loader, metadata-editor, thrall, leases, cropper, collections, kahuna (merged by @paperboyo 9 minutes and 41 seconds ago) Please check your changes!

[prout-bot]

Seen on media-api (merged by @paperboyo 9 minutes and 47 seconds ago) Please check your changes!