Attach multiple fixes to a single report

[arogge]

Problem

Currently when I press "Confirm Fix" I can only select a single version the fix is applied to, a single branch and a single commit id.

In our development process we usually have multiple individual fixes to multiple supported versions. Basically we would need to be able fill that "Confirm Fix"-Form multiple times for the same report.

Real-World-Example

We have a report for version 18.2 and newer
The current version is 21.0.0, but we still support 20.y.z and 19.2.z, but not 18.2.z.

As a result there will be a fix

• on branch younameit-21 that will be released as 21.1.0
• on branch younameit-20 that will be released as 20.0.6
• on branch younameit-19.2 that will be released as 19.2.12

Currently I can only add one of these fixes, while I should be able to add them all.

[psmoros]

Also #2287