Feature: Additional option for updating containers - multi-select

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Right now we have the option to update individual containers OR "Update All" (by stack). Would be nice to have the option to multi-select several containers and "Update Selected" as an additional middle-ground update option.

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Additional note: It appears that the current behavior has a bit of an issue? If I trigger one container to update, I cannot trigger another container to update until the previous one was completed. Selecting another container update seems to do nothing.