Add option to re-prompt at intervals after user accept/ignore

[sampengilly]

Allow the prompt to be shown again at intervals after each user action (accept/ignore).

Track the time each time the AgreeShowDialog preference is set to false. When checking if this value is false, or it with the result of isOverLastAgreeShowFalseDate() to determine if it has been X time units since AgreeShowDialog was set to false, a result of true will continue with the rest of the evaluation.

Defaults to off. Setting a time unit will turn the check on. Date of AgreeShowDialog = false is always tracked

[qlty-cloud-legacy[bot]]

Code Climate has analyzed commit 57d7b50c and detected 3 issues on this pull request.

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