Action Invoker source/target doesn’t work with `wait` meta action

**Describe the bug**
ActionInvoker is null after `wait` action.

**Version (commit hash)**
d2ad04b3f53abf5738ab2e178f3a2796d52e66fe

**To Reproduce**
Steps to reproduce the behaviour:
1. Create a script
2. Create any event which has „invoker”
3. Add action `wait`
4. Add any action with invoker source
5. Test in game - doesn’t work, because invoker is null there

**Expected behaviour**
Action Invoker should work as expected after `wait` action.

**Proposed solution**
Best option would be to change TC to pass invoker here https://github.com/TrinityCore/TrinityCore/blob/master/src/server/game/AI/SmartScripts/SmartScript.cpp#L1542

Another option would be to change invoker to storedTarget in the editor, but there is a risk, this storedTargetID will be taken already. We can inform user during exporting that some storedTarget will be reserved?

Start by reproducing the script described in the issue: an event with an invoker, a wait action, and a later action using the invoker source. Inspect the editor's handling of invoker and storedTarget during export, then review TrinityCore's SmartScript.cpp around line 1542. Done means the later action still receives the expected invoker after wait.

Written by the indexing model from the issue text.