Add Transaction (CA) feature tests

[JonathanLevi]

Description

We need to have a set of tests covering the behavior and functionality using various (Behave) scenarios around Enrollment.

In particular, with a focus on the Transaction CA (TCA) functionality of Membership Services.

Motivation

At this point, even a small number of positive- and negative- flows will go a long way, both for development, testing but also as an easy way for new users to learn about Hyperledger fabric and its capabilities.

Context

Membership Services end-to-end integration tests. A sub-task of 1575

[mastersingh24]

I spoke with @JonathanLevi and I'll take this one on

[bmos299]

@mastersingh24 Thanks. @srderson can you please add a behave label to track all the issues involving behave work? Thanks.