Support for time delay on auto-update of container image

[chrisbennight]

It would be great if the auto update option included an optional field to indicate a delay in hours, after a new image was detected, before it would be applied (specific to the auto update feature). During that delay period if a newer image was detected the newer image would superscede the previous pending install (i.e. only the latest image would get installed after the requisite delay)

Intent here is to allow bugs, issues, etc. some time to be worked out while still enjoying the benefits of automatic unattended updates.

Here's some references where this was asked for / and a pr for it against watchtower
containrrr/watchtower#1884
containrrr/watchtower#426
https://www.reddit.com/r/selfhosted/comments/1ddm8nm/watchtower_no_defer_option/