[roll] Roll fuchsia [test_manager] Allow test resources to extend realm lifetime

Today, the lifetime of a test realm is loosely tied to
actions taken by a test executor. Specifically, the Archivist under a
test realm must remain alive long enough for the executor to drain logs
collected from the test realm.
We'll soon have custom artifacts, which will be exported via a handle
to storage accessed by a component in the test realm. Test manager will
need to keep realms alive while an executor is accessing the storage,
otherwise, component manager is free to delete the storage. Unlike
logs, the handles for accessing custom artifacts must be created after
the test terminates.

This change provides the `run_test' method with a mutable reference to
the running suite, which allows it to store signals that can be used to
keep the realms alive. It also moves the creation of log tasks into
'run_test'.

Original-Bug: 75690
Testing: Pure refactor, test with existing integ tests
Multiply: test_manager_test

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/580306
Original-Revision: a205521ed964249de4d528467b7830580f9d1e3c
GitOrigin-RevId: 66b69e7d9ba9522cda45b4998068de5f2e0f5197
Change-Id: I948268564505b7c347bcb8480f31989d174d0c79
diff --git a/stem b/stem
index 8cbd182..8caeca5 100644
--- a/stem
+++ b/stem
@@ -10,7 +10,7 @@
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-             revision="4e20da3687b1e292a95a0b75a4c7143cd342caa9"/>
+             revision="a205521ed964249de4d528467b7830580f9d1e3c"/>
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