Allows nav:goto to ignore navigation locks by default, adds a new setting to enforce navigation lock per action.

[FrenjaminBanklin]

Closes #1948

Adds an 'ignore lock' toggle to nav:goto actions which defaults to true, allowing all existing button-based navigation to continue working while also allowing authors to respect navlocks, or at least inform them when they do not.

[deundrewilliams]

The ignore navigation toggle works, allowing navigation when it's switched on, but it only works with 'Go to' and not 'Go to previous page' or 'Go to next page'. Should the toggle be added to these options, or is it fine to not have it since the user can just enter the ID of the next/prev page in the field?

[FrenjaminBanklin]

@jpeterson976 worked on this more recently so he may remember if the 'Next Page' and 'Previous Page' buttons still worked regardless of the navigation being locked, but I don't think they did. If not, it would be inconsistent to allow a triggered nav:prev or nav:next action to optionally ignore the navigation lock.

It wouldn't be hard to enable the new optional behavior for nav:prev and nav:next, and I thought about doing so, but I think it makes sense for those two to respect navigation locks at all times based on the above assumption. With nav:goto I can think of situations where authors want the nav to stay locked but for specific situations to still move students around in the content.

[jpeterson976]

I checked my old PR, nav:prev and nav:next did not previously work when navigation was locked, so Brandon's assumption was correct.

The new toggle switch also works as advertised, so this gets my approval.