Support Dashboard sharing settings API

[UnseenWizzard]

Dashboard sharing settings are now available as an API in EAP

monaco should support the API to allow automatically sharing dashboards, instead of still requiring manual/UI interaction.

Notably the API is part of the Dashboard API (under /dashboards/{id}/sharing) and requires the ID of the dashboard while only offering GET and PUT.

These configurations will thus usually depend on a dashboard configuration directly, and not follow the "POST if no config exists/PUT if exists" patter of regular configuration.

[patrickpichler]

Related to #337 and #213