Add string representations to most used objects

[perolavsvendsen]

Current experience:

[1] mycases = sumo.cases.filter(user="peesv")
[2] mycases
>>> <fmu.sumo.explorer.objects._search_context.SearchContext at 0x20d08fe3b90>

[3] len(mycases)
>>> 310

[4] mycases = sumo.cases.filter(user="NoSuchName")
[5] mycases
>>> <fmu.sumo.explorer.objects._search_context.SearchContext at 0x20d08fe3b90>

[6] len(mycases)
>>> 0

Suggest we add representations, so that this returns something more useful? Not sure exactly what to show, so this needs some discussion. But simple suggestion could be to just print the length of the context. I.e. it is important to know if this is an empty search context or not. Perhaps explicitly show when resulting length is 0.

Possible other suggestions:

• First + last two names of collection?
• Unique data types (class)?