Ability to choose where new Issues will be added in the Backlog

As per GHS-10472, as a JIRA Agile User I'd like to choose whether the issues I'm creating are added to the bottom or the top of the backlog, or if it should be added above the current selected issue.

Some users may think a new issue should put it to the bottom of the backlog to prevent accidentally giving the issue a priority while others may prefer the current behavior, so giving the ability to chose which suits better for the users would be great.

Current Behavior:

• When 1 or more issues have been selected -> rank the new issue after the lowest ranked selected issue
• When no issue is selected -> rank the issue at the top of where the plan mode is currently scrolled.
• When not on plan mode, new issues are ranked to the bottom of the backlog