Replay: avoid recursion when adding subscriptions

[bresch]

Solved Problem

readAndAddSubscription uses nextDataMessage to find the first corresponding data and nextDataMessage calls readAndAddSubscription when it finds a new message definition.
This works but I don't think the recursion was done by design...

Solution

Sequentially add and setup each subscription without recursion.

The check for msg_type == (int)ULogMessageType::ADD_LOGGED_MSG also helps when some other messages exist at the same time, leading to strange output:

WARN  [replay] Topic @� not found internally. Will ignore it
WARN  [replay] Topic @� not found internally. Will ignore it
WARN  [replay] Topic @� not found internally. Will ignore it
WARN  [replay] Topic A� not found internally. Will ignore it
WARN  [replay] Topic <� not found internally. Will ignore it
WARN  [replay] Topic Q� not found internally. Will ignore it
WARN  [replay] Topic B� not found internally. Will ignore it

Test coverage

Tested on a SITL log and a real flight from 1.16 (https://review.px4.io/plot_app?log=8863bef0-17e4-4315-b386-e1818d7d24f8)

[dagar]

We should really get some basic replay testing in place. It could be as simply as running a SITL test, replaying, and performing a basic comparison.