PCI Title Suggestions: Implement "Intent" feature

[acicovic]

Is your feature request related to a problem?

The underlying API for our Title Suggestions feature supports an intent parameter, but we aren't taking advantage of it in the Title Suggestions feature/UI.

Describe the solution you'd like

Implement an "Intent" feature within Title Suggestions, by introducing a control for it. Intent can be combined with our existing Tone and Persona fields, since the underlying API supports processing them simultaneously. We could also phase out any of the existing fields if we conclude that intent can replace any of them.

Potential steps/actions:

• [ ] Discuss/design (@LauraKalnicky / @dabowman).
• [ ] If we're considering removing any existing fields, see what usage data we have on them.
• [ ] Implement.

Additional context

intent is a string parameter. The currently supported intents are:

• "breaking"
• "informative"
• "engagement"
• "social"
• "opinion"
• "investigative"

The default intent is "none". It's what is currently being used since we don't have an Intent field in the UI.