feat(aci): Database-tracked coordinated task-based DetectorGroup backfill

[kcons]

This approach allows the backfill to be run to completion and tracked without creating significant task backlog.
The first phase is a one-time status row creation, which is run in a task loop.
From there, we can start triggering the coordinator periodically and having it manage scheduling tasks for work items, first very slowly to verify, then in increasing volume.
We can ensure that the capacity cost of this backfill is relatively fixed regardless of processing rate, and failed tasks can naturally be rescheduled without them starving out possibly successful tasks.

The downside is a new table and some weird infra that has one intended use.
But, the alternates aren't great either.

[github-actions]

This PR has a migration; here is the generated SQL for src/sentry/workflow_engine/migrations/0094_add_error_backfill_status.py

for 0094_add_error_backfill_status in workflow_engine

--
-- Create model ErrorBackfillStatus
--
CREATE TABLE "workflow_engine_error_backfill_status" ("id" bigint NOT NULL PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY, "date_updated" timestamp with time zone NOT NULL, "date_added" timestamp with time zone NOT NULL, "status" varchar(20) NOT NULL, "detector_id" bigint NOT NULL UNIQUE);
ALTER TABLE "workflow_engine_error_backfill_status" ADD CONSTRAINT "workflow_engine_erro_detector_id_6e5eb8d9_fk_workflow_" FOREIGN KEY ("detector_id") REFERENCES "workflow_engine_detector" ("id") DEFERRABLE INITIALLY DEFERRED NOT VALID;
ALTER TABLE "workflow_engine_error_backfill_status" VALIDATE CONSTRAINT "workflow_engine_erro_detector_id_6e5eb8d9_fk_workflow_";
CREATE INDEX CONCURRENTLY "workflow_engine_error_backfill_status_status_3d9773bb" ON "workflow_engine_error_backfill_status" ("status");
CREATE INDEX CONCURRENTLY "workflow_engine_error_backfill_status_status_3d9773bb_like" ON "workflow_engine_error_backfill_status" ("status" varchar_pattern_ops);
CREATE INDEX CONCURRENTLY "errbkfl_stat_upd_idx" ON "workflow_engine_error_backfill_status" ("status", "date_updated");

[getsantry]

This issue has gone three weeks without activity. In another week, I will close it.

But! If you comment or otherwise update it, I will reset the clock, and if you remove the label Waiting for: Community, I will leave it alone ... forever!

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"A weed is but an unloved flower." ― Ella Wheeler Wilcox 🥀