Describe the feature or problem you’d like to solve

A couple things have risen to the level of things where we feel like adding the ability to configure a set of preferences for gh would be appropriate.

Proposed solution

Create a gh config command (open to other ideas on the naming, but this is what we were thinking).

Initially, this will include two preferences:

• SSH vs https default remote preference
• Default editor for use with gh

Our thinking is to have a config file, probably a yaml file, that contains these preferences and is where we read from when they use the tool. However, we'd also like a simpler and less error-prone way to change a particular preference, so we were thinking of:

gh config <key> <value>

For example, to change your default editor, you could: gh config editor vim (I don't know if this is exactly what the command would be, but that's the idea).

Additional context

This is directly related to #546 and #308.