StreamConfig initialization with options pattern

[ppilev]

Description
This change will allow configuration settings used to initialize instances of ClientConfig, ConsumerConfig and ProducerConfig to be reused for StreamConfig initialization.

Changes

• [x] refactor StreamConfig to support proper property initialization through .net options pattern
• [x] add unit test

Problem Details Currently StreamConfig is derived from Dictionary<string, dynamic> thus during the instance initialization the public property setters are ignored, the configuration values are stored directly into the base class (the dictionary) and the type conversion (i.e. for enum values) is not handled properly, i.e. consider the following configuration in appsettings.json file:

{
  "Kafka": {
    "ConsumerConfig": {
      "AutoOffsetReset": "Error"
    }
  }
}

when applied through options pattern this configuration won't initialize config.AutoOffsetReset property with Error but just will create the following entry in the underlying dictionary, however such entry has no meaning to StreamConfig at all

{ "AutoOffsetReset", "Error" }

Expected behavior For expected behavior please follow the implementation of CreateStreamConfigThroughOptionsPattern test from this PR.