Fix map panning issues related resource info modal

[ravimakhijapi]

Change Summary

Addresses #527. Introduces lastResourcePan in redux state to supersede prior mapCenter in redux, and currentLat/currentLon component state in <ReactGoogleMaps>, which helps properly track the last pan caused by the user clicking a pin or on the "Near Me" button.

Change Reason

Fixes various issues as described in detail in issue #527, where the map was panning when it shouldn't be, and wasn't panning when it should be, depending on the scenario.

Related Issue: #527