Add functionality for Well Completions Module

[jorgenherje]

Add functionality:

• Consider adding dropdowns for time steps if number of available time steps becomes large (slider might be inaccurate/bad functionality with many time steps).
• Wells per page/horizontal slider functionality for plot
• Zone selection (Awaits zones parent/child info in Sumo. Functionality: see zone selector in old plugin)
• Sort/Group by Attributes functionality (Awaits well attributes in Sumo. Functionality: see view control in old plugin)
• Filter by attributes (Awaits well attributes in Sumo. Functionality: see smart node selector in filter of old plugin)
• Sort zones according to depth (Awaits: fmu-dataio data requests #736 and Well Completions: Need info of stratigraphy/zone order from most shallow to deepest #761)

Also see: #256

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Awaiting: Well attributes from SUMO or other services?