* feat!: update timestamp of catalog-info-changed signal
When producing the catalog-info-changed signal, we
now get the timestamp of the change from modulestore,
rather than relying on the current time at the time
of the event send.
BREAKING CHANGE: This will adjust the meaning of the
time metadata for new catalog-info-changed events.
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Co-authored-by: Robert Raposa <rraposa@edx.org>