This commit also renames the legacy event variable to
legacy_event from event because same event is sent
twice if we keep only single variable and change its
value. This was happening because the event value was
changed when the first send_event was actually executed.
We pass the realm_linkfiers list to notify_linkifiers instead of
computing it in notify_linkifiers itself, because its caller
functions will require the list in further commits for creating
RealmAuditLog entries.
Add none-checks, rename variables (to avoid redefinition of
the same variable with different types error), add necessary
type annotations.
This is a part of #18777.
Signed-off-by: Zixuan James Li <359101898@qq.com>