Delay stream creation until the next loop tick

[glbrntt]

Motivation:

A recent change allowed stream creation to run immediately if the caller was on the correct event loop. Normally that's fine, however, it opens up a code path where streams can become activated twice which leads to a crash.

Modifications:

• Delay stream creation until the next loop tick
• Add a loop tick to tests which now require it

Result:

Avoid re-entrantly activating streams twice.