Add a button to remove an inactive download from the list in DownloadMonitor

[VilppeRiskidev]

• Added a corresponding vuex mutation
• Separated indexOfDownloadProgress function
• Removed the "There was a mismatch between download update's assign ID" check as that is now expected behavciour when a download is removed from the list.

[VilppeRiskidev]

"There was a mismatch between download update's assign ID" behaviour is now normal, unless there's better way of implementing this, so I removed the logging for that.

[anttimaki]

Nice, code-wise this looks good to me. Couldn't resist leaving some nitpicks related to code style, but they're not blockers.

I would perhaps consider the UI again though. The remove button is positioned kind of awkwardly. Vertically it doesn't seem to be aligned in any sensible way (I know it's positioned at the top of its container but that's not what the user sees due to other whitespace around it). Horizontally there's less margin between the button and progress bar than the button has on its other sides.

Take into account that in the future the failed downloads would have two buttons here, "remove" and "retry". So something smaller like icon-sized button, without the borders and padding of the button, might be easier to deal with. I can't recall if there's support for such buttons in the code base currently.

And to clarify the UI side isn't necessarily a blocker either.

[anttimaki]

@VilppeRiskidev What's the status of this PR? There's a force push but doesn't seem the review comments are addressed one way or another.

[VilppeRiskidev]

The comments have been addressed.
Action button's styles look good to my eye now 🤷‍♂️ .

[anttimaki]

The icon is a bit large but otherwise this looks nice now.