Revise the algorithm for generating simplified plan descriptions

[dmgav]

Revise the algorithm for simplifying plan descriptions in the function bluesky_queueserver.conversions.simplify_plan_descriptions(). The algorithm must be able to recognize a predefined set of types, reliably identify if the type is a list (typing.List or typing.Tuple) and the type of list elements if it is one of supported types (int, float or str). If it is recognized, that the scalar type or element type is not supported, the type should be omitted. The default value should be decoded from the full description and sent as is.

The required modifications are relatively simple. The goal is to completely omit unsupported types in simplified descriptions, which may be convenient for autogenerating forms in web applications. It is assumed that the plans will use only supported parameter types if web forms are expected to be generated automatically based on plan descriptions.