Support for fully asynchronous humbug reports

[zomglings]

Currently, users can POST /humbug/reports with sync=true or sync=false.

When sync=true, response is only sent after report is written into database.

When sync=false, response is sent after report is written to redis queue (with fallback to database).

This doesn't result in a significant speedup - the sync=false takes ~83% of the time that sync=true takes:

"bash" "-c" "time for i in {1..100}; do curl -s -H \"Content-Type: application/json\" -H \"Authorization: Bearer 6924ac70-f2b4-4444-a26b-7db8c15bf694\" -X POST https://spire.bugout.dev/humbug/reports -d \"{\\\"title\\\": \\\"Report (postgres) lol\\\", \\\"content\\\": \\\"content 5\\\", \\\"tags\\\": [\\\"a\\\", \\\"b\\\"]}\" >/dev/null ; done"

real    0m35.016s
user    0m0.777s
sys    0m0.343s

"bash" "-c" "time for i in {1..100}; do curl -s -H \"Content-Type: application/json\" -H \"Authorization: Bearer 6924ac70-f2b4-4444-a26b-7db8c15bf694\" -X POST https://spire.bugout.dev/humbug/reports?sync=true -d \"{\\\"title\\\": \\\"Report (postgres) lol\\\", \\\"content\\\": \\\"content 5\\\", \\\"tags\\\": [\\\"a\\\", \\\"b\\\"]}\" >/dev/null ; done"

real    0m42.723s
user    0m0.878s
sys    0m0.279s

(although it may be faster when requests are made concurrently).

I propose we change sync={true|false} to syncMode={async|enqueue|commit}.

If syncMode=async, the report will be published as a background task and the endpoint will immediately return 200.

If syncMode=enqueue, then we will do what sync=false currently does.

If syncMode=commit, then we will do what sync=true currently does.