Feat: Add support for named start

[vikaspotluri123]

Adds functionality similar to the stop command - ghost start {name} now works as ghost stop {name} always has

I realized this wasn't a thing as I was testing #765, and given the Stop command already has this functionality, I figured it would be a 5 minute fix, but it turns out both the Start and Stop Command Unit tests aren't super dry, so I ended up going down the rabbit hole of drying up the tests. It might be easier to review commit by commit 😬

I know this coincides w/ the release of 1.9.0; I don't think it will make much of a difference if this gets released before or afterwards.

[coveralls]

Coverage remained the same at 100.0% when pulling 593d851da04fdbf1511079931ba1d7a695086229 on vikaspotluri123:feat/named-start into 77188efab64f61810854d020ca14ba56246938a0 on TryGhost:master.

[vikaspotluri123]

@acburdine everything's been fixed now 😄

[vikaspotluri123]

Rebased! 🙃

[vikaspotluri123]

Couple things:

• Do we want to add parity between stop, start, and update? There is a feature request for update --all, and we can add support for start --all as well.
• Should get-instance be used / run in the System Class?

[github-actions[bot]]

Our bot has automatically marked this PR as stale because there has not been any activity here in some time. If we’ve failed to review your PR & you’re still interested in working on it, please let us know. Otherwise this PR will be closed shortly, but can always be reopened later. Thank you for understanding 🙂

[ErisDS]

Is there anything outstanding that prevents us from merging this PR? There may be more things we want to do, but if this change is valid and useful, let's get it in? 😄

[vikaspotluri123]

Nothing on my side!