Use g_task_set_source_tag on all of our async methods
This is supposed to help with debugging and profiling per the docs for
g_task_set_name, which is automatically called by g_task_set_source_tag in
glib >= 2.76.0 which is our minimum requirement.
Testing Done:
Consulted with the turtles
Reviewed at https://reviews.imfreedom.org/r/2955/
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