Add support to localhost urls while debugging

[sergiolms]

Description

These changes will allow testing local development on APIs and backend services of gk-dev. With this, you can now set the following settings in settings.json (made up urls for the example):

{
	"gitkraken.env": "local",
	"gitkraken.url": {
		"api": "http://localhost:1314/api",
		"gkdev": {
			"base": "http://localhost:1314",
			"api": "http://localhost:1314/gkdev/api"
		}
	}
}

NOTE: URLs will only be applied when gitkraken.env is set to local. Also, the local environment has the same restrictions as dev and staging (only available if it's pre-release or debugging).

Checklist

• [x] I have followed the guidelines in the Contributing document
• [x] My changes follow the coding style of this project
• [x] My changes build without any errors or warnings
• [x] My changes have been formatted and linted
• [x] My changes include any required corresponding changes to the documentation (including CHANGELOG.md and README.md)
• [x] My changes have been rebased and squashed to the minimal number (typically 1) of relevant commits
• [x] My changes have a descriptive commit message with a short title, including a Fixes $XXX - or Closes #XXX - prefix to auto-close the issue that your PR addresses