Feature request: easily list/explore all objects (in schema)

In navigating a database with a lot of schemas, and a lot of different type of objects (tables, views, functions, data types, trigger, etc), there is a lot of friction in exploring the database because you have to manually list each type of object. And with schemas, the non-intuitive search path semantics make it extra hard.

I think it would be a great feature if one could just (as a figure of speech) `cd` into a schema and run `ls [-l]`, which would then show everything and what it is.

Start by reviewing how pgcli currently lists tables, views, functions, data types, and triggers, and how schema navigation and search paths are represented. Define the scope and output for entering a schema followed by `ls` or `ls -l`; done means one command exposes the requested object types with useful type and detail information.

Written by the indexing model from the issue text.