Markers not showing / updating / deleting on low-use servers or when disconnected

[CoryFoy]

Describe the bug
When adding / updating / deleting a marker when either connected to a low-use TAK Server or not connected at all, markers may not initially update until other actions are taken (such as adding another marker) even though the haptic feedback indicates the action was taken.

To Reproduce
Steps to reproduce the behavior:

1. Disconnect from all TAK Servers
2. Long-press on the map

Expected behavior
Expect to see a marker show up. But it doesn't (until you long-press on another part of the map)

Smartphone (please complete the following information):

• Version: [e.g. 22] 1.1.76
• App Store or TestFlight?: App Store

Additional context
The issue is that the marker is being created, but the notification system hasn't merged it from the background context into the main context by the time the map tries to query for it. Effectively this is a race condition. It doesn't matter on a busy server because enough actions are happening that it will get picked up the next time markers get updated. But the fix is simply to perform add / update / delete actions of markers on the main viewcontext since the user is interacting with the map at that point.