Cannot add identity to wallet using gateway

[Jakeeyturner]

Description

In our v1.0.19 release, we broke the ability to add an identity to a wallet, by connecting to the gateway and providing an enrollment ID and secret.
This is also exposed when you create a new wallet (and it follows the same flow).

What happens is that if you add a gateway, and try to use it, then it doesn't appear in the list of gateways to use.

Expected Behavior

The gateway doesn't show up in the list of gateways to connect to.

Actual Behavior

We should see all gateways and be able to use them to enroll with,

Possible Fix

Steps to Reproduce

Existing issues

• Stack Overflow issues
• GitHub Issues

Log File

Your Environment

• IBM Blockchain Platform Extension Version:
• Visual Studio Code version:
• Environment name and version (e.g. Node.js v8.12.0, npm v6.4.1):
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