[TIMOB-11976] Android: More performance optimizations for image handling

See TIMOB-11282 for the test case here. There is additional room for optimization over what was done in that ticket. Caching the resized images would be of benefit -- they are not currently cached, and resized by AsyncTasks as needed. In the cace of TIMOB-11282 the resized images were only a few K bytes each, and they all would have fit into a fairly small cache (under 100 KB in that case). It's probably best to pick a maximum cache size and manage by the bytes used in the cache. The images retrieved from the internet are cached in the full size, then later on they are resized as needed. That cache is shared with other components, so it can be kept and another layer of caching for the resized images can be added on top of it. It's possible that a better use of threads can be made in image handling. The UI thread may still be doing more work than needed right now. The path through the other various AsyncTasks and threads may not be as efficient as it could be. If the work done on this ticket does not resolve the issue completely, please create another Jira ticket with remaining work items listed.