Add GoodJob gem.

This is the first step towards replacing DelayedJob with GoodJob. Compared to
DelayedJob:

* GoodJob supports Rails 7 (DelayedJob is currently a blocker for Rails 7
  because it has a version bound on ActiveRecord <6.2).
* GoodJob has a builtin admin dashboard.
* GoodJob supports threaded job workers.
* GoodJob supports scheduled cronjobs.
* GoodJob supports healthchecks for workers.
* GoodJob uses Postgres notifications instead of polling to pick up new
  jobs. This allows jobs to be picked up faster and scales better with
  large numbers of workers.

https://github.com/bensheldon/good_job

db/structure.sql

@@ -37,6 +37,20 @@ CREATE EXTENSION IF NOT EXISTS pg_trgm WITH SCHEMA public;
 COMMENT ON EXTENSION pg_trgm IS 'text similarity measurement and index searching based on trigrams';
 
 
+--
+-- Name: pgcrypto; Type: EXTENSION; Schema: -; Owner: -
+--
+
+CREATE EXTENSION IF NOT EXISTS pgcrypto WITH SCHEMA public;
+
+
+--
+-- Name: EXTENSION pgcrypto; Type: COMMENT; Schema: -; Owner: -
+--
+
+COMMENT ON EXTENSION pgcrypto IS 'cryptographic functions';
+
+
 --
 -- Name: pgstattuple; Type: EXTENSION; Schema: -; Owner: -
 --
@@ -821,6 +835,41 @@ CREATE SEQUENCE public.forum_topics_id_seq
 ALTER SEQUENCE public.forum_topics_id_seq OWNED BY public.forum_topics.id;
 
 
+--
+-- Name: good_job_processes; Type: TABLE; Schema: public; Owner: -
+--
+
+CREATE TABLE public.good_job_processes (
+    id uuid DEFAULT gen_random_uuid() NOT NULL,
+    created_at timestamp(6) without time zone NOT NULL,
+    updated_at timestamp(6) without time zone NOT NULL,
+    state jsonb
+);
+
+
+--
+-- Name: good_jobs; Type: TABLE; Schema: public; Owner: -
+--
+
+CREATE TABLE public.good_jobs (
+    id uuid DEFAULT gen_random_uuid() NOT NULL,
+    queue_name text,
+    priority integer,
+    serialized_params jsonb,
+    scheduled_at timestamp without time zone,
+    performed_at timestamp without time zone,
+    finished_at timestamp without time zone,
+    error text,
+    created_at timestamp(6) without time zone NOT NULL,
+    updated_at timestamp(6) without time zone NOT NULL,
+    active_job_id uuid,
+    concurrency_key text,
+    cron_key text,
+    retried_good_job_id uuid,
+    cron_at timestamp without time zone
+);
+
+
 --
 -- Name: note_versions; Type: TABLE; Schema: public; Owner: -
 --
@@ -2758,6 +2807,22 @@ ALTER TABLE ONLY public.forum_topics
     ADD CONSTRAINT forum_topics_pkey PRIMARY KEY (id);
 
 
+--
+-- Name: good_job_processes good_job_processes_pkey; Type: CONSTRAINT; Schema: public; Owner: -
+--
+
+ALTER TABLE ONLY public.good_job_processes
+    ADD CONSTRAINT good_job_processes_pkey PRIMARY KEY (id);
+
+
+--
+-- Name: good_jobs good_jobs_pkey; Type: CONSTRAINT; Schema: public; Owner: -
+--
+
+ALTER TABLE ONLY public.good_jobs
+    ADD CONSTRAINT good_jobs_pkey PRIMARY KEY (id);
+
+
 --
 -- Name: ip_bans ip_bans_pkey; Type: CONSTRAINT; Schema: public; Owner: -
 --
@@ -3605,6 +3670,48 @@ CREATE INDEX index_forum_topics_on_title_tsvector ON public.forum_topics USING g
 CREATE INDEX index_forum_topics_on_updated_at ON public.forum_topics USING btree (updated_at);
 
 
+--
+-- Name: index_good_jobs_on_active_job_id_and_created_at; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE INDEX index_good_jobs_on_active_job_id_and_created_at ON public.good_jobs USING btree (active_job_id, created_at);
+
+
+--
+-- Name: index_good_jobs_on_concurrency_key_when_unfinished; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE INDEX index_good_jobs_on_concurrency_key_when_unfinished ON public.good_jobs USING btree (concurrency_key) WHERE (finished_at IS NULL);
+
+
+--
+-- Name: index_good_jobs_on_cron_key_and_created_at; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE INDEX index_good_jobs_on_cron_key_and_created_at ON public.good_jobs USING btree (cron_key, created_at);
+
+
+--
+-- Name: index_good_jobs_on_cron_key_and_cron_at; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE UNIQUE INDEX index_good_jobs_on_cron_key_and_cron_at ON public.good_jobs USING btree (cron_key, cron_at);
+
+
+--
+-- Name: index_good_jobs_on_queue_name_and_scheduled_at; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE INDEX index_good_jobs_on_queue_name_and_scheduled_at ON public.good_jobs USING btree (queue_name, scheduled_at) WHERE (finished_at IS NULL);
+
+
+--
+-- Name: index_good_jobs_on_scheduled_at; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE INDEX index_good_jobs_on_scheduled_at ON public.good_jobs USING btree (scheduled_at) WHERE (finished_at IS NULL);
+
+
 --
 -- Name: index_ip_bans_on_category; Type: INDEX; Schema: public; Owner: -
 --
@@ -5073,6 +5180,7 @@ INSERT INTO "schema_migrations" (version) VALUES
 ('20211018045429'),
 ('20211018062916'),
 ('20211023225730'),
-('20211121080239');
+('20211121080239'),
+('20220101224048');