Template improvements II

[amcaplan]

WHY are these changes introduced?

The bug issue template is still a bit rough around the edges, here are some clear improvements.

WHAT is this pull request doing?

Improving the UX of the bug issue template

How to test your changes?

In the console, try:

begin
  invalidcommand
rescue => e
  ShopifyCLI::GitHub::IssueURLGenerator.error_url(e)
end

and see the stacktrace included as a param.

Update checklist

• I've added a CHANGELOG entry for this PR (if the change is public-facing)
• I've considered possible cross-platform impacts (Mac, Linux, Windows).
• I've left the version number as is (we'll handle incrementing this when releasing).

[gonzaloriestra]

I wouldn't include these changes as they are not much relevant for the CLI users, arent' they?

Suggested change

	* [#2001](https://github.com/Shopify/shopify-cli/pull/2001): Improve Bug Issue Template
	* [#2004](https://github.com/Shopify/shopify-cli/pull/2004): Template improvements II

[amcaplan]

They include changes to URL generator which is a user-facing change. @pepicrft, care to opine?

[pepicrft]

If we surface improvements through the CLI I think it justifies an entry in the CHANGELOG. It'd have been different if the change was only in the template.