Unbound/not-fixed-size MaxFilterHeightRange

[i-norden]

Currently MaxFilterHeightRange expects an int to define a static window size for the maximum number of epochs a filter query can look back from the current latest tipset. As the chain progresses, this window shifts forward making it impossible to set a boundary at a specific epoch.

Easy current work around if the goal is to simply allow the entire FEVM range (the only range which has FEVM events to filter) is to set it to the current epoch. This will stretch far back below the FEVM activation epoch (2,683,348) for a very long time. But if instead one wanted to define a specific epoch above 2,683,348 as the filter query boundary it is currently not possible.