[viz-theme] Unintuitive submit behavior of settings input field

[Kristoffer Magnusson]

The behavior of gatsby-theme-rpsych-viz/src/components/SettingsInput.js is unintuitive. Currently any new values need to be submitted by hitting enter - which many users miss.

Possible solutions:

• auto-submit any changes. This behavior was used previously, but it was also annoying.
• auto-submit but debounce while users type
• add label under the field to "hit enter to submit" if there's unsubmitted changes
• add a clear submit button that will submit all fields, and clearly show if there's unsubmitted fields