add ability to pause sources for render testing

[ansis]

The regressions/mapbox-gl-js#8817 render test relies pausing a source so that no new tiles are loaded. This lets the test render a tile beyond it's ideal zoom range. I think mapbox-gl-native does not currently have a way of doing this.

I opened this issue to cover why this render test is skipped. If it seems like implementing this in -native isn't worth it feel free to close this issue

[stale]

This issue has been automatically detected as stale because it has not had recent activity and will be archived. Thank you for your contributions.

[stale]

This issue has been automatically detected as stale because it has not had recent activity and will be archived. Thank you for your contributions.