Feature info doesn't always update when time changes

[kring]

Ideally, anything displayed in the feature info would update whenever the layer's time changes, and sometimes it does. But there are cases where it doesn't:

• Feature info for imagery layers (e.g. WMS) never updates when the time changes. Doing so would require that the pick (GetFeatureInfo for WMS) be run again whenever we move to a new interval.
• ~Feature info for TableCatalogItem updates when the time is changed using the timeline (including the date picker on the timeline), but it does not update when using the date picker on the workbench. Fixing this is tricky because there's currently no event that gets raised when the time changes via that mechanism, so the FeatureInfoSection can't subscribe to it.~ ** this is fixed in v8 (@nf-s )

[kring]

See comment in FeatureInfoSection.jsx, setSubscriptionsAndTimeouts function.

// This is probably a DataSourceClock because the catalog item is using its own clock.
// But we currently have no way of subscribing to changes to it.
// See https://github.com/TerriaJS/terriajs/issues/2736