[maps] display tooltip message when layer does not support "edit features"

[nreese]

Currently, "Edit features" layer action is not displayed if the layer does not support feature editing. Instead, "Edit features" action should always be displayed but disabled (for vector layers) if the layer does not support feature editing. That way, feature editing is not hidden in the UI and users will always know why a layer can/cannot edit features.

[elasticmachine]

Pinging @elastic/kibana-gis (Team:Geo)

[nreese]

The following changes should be made to TOCEntryActionsPopover.

• supportsFeatureEditing and isFeatureEditingEnabled should be combined into a single piece of state canEditFeatures.
• New piece of state editFeaturesDisabledReason should be added.
• canEditFeatures and editFeaturesDisabledReason should be set in _loadFeatureEditing by calling this.props.layer.supportsFeatureEditing
• Action EDIT_FEATURES_LABEL should be displayed if layer is vector layer. Action should be disabled if canEditFeatures is false with tooltip containing editFeaturesDisabledReason.

VectorLayer and VectorSource supportsFeatureEditing method should be updated to return Promise<boolean, editFeaturesDisabledReason>. Implementations of supportsFeatureEditing should provide user understandable reasons why feature editing is not supported (which configurations or constraints do not allow for feature editing).

[elasticmachine]

Pinging @elastic/kibana-presentation (Team:Presentation)