feat: add connection statistics for workspace agents (#6469)

* fix: don't make session counts cumulative

This made for some weird tracking... we want the point-in-time
number of counts!

* Add databasefake query for getting agent stats

* Add deployment stats endpoint

* The query... works?!?

* Fix aggregation query

* Select from multiple tables instead

* Fix continuous stats

* Increase period of stat refreshes

* Add workspace counts to deployment stats

* fmt

* Add a slight bit of responsiveness

* Fix template version editor overflow

* Add refresh button

* Fix font family on button

* Fix latest stat being reported

* Revert agent conn stats

* Fix linting error

* Fix tests

* Fix gen

* Fix migrations

* Block on sending stat updates

* Add test fixtures

* Fix response structure

* make gen

coderd/database/migrations/000108_workspace_agent_stats_connection_latency.down.sql

@@ -0,0 +1 @@
+ALTER TABLE	workspace_agent_stats ALTER COLUMN connection_median_latency_ms TYPE bigint;

coderd/database/migrations/000108_workspace_agent_stats_connection_latency.up.sql

@@ -0,0 +1 @@
+ALTER TABLE	workspace_agent_stats ALTER COLUMN connection_median_latency_ms TYPE FLOAT;

coderd/database/migrations/testdata/fixtures/000106_pre_workspace_agent_stats_connection_latency.up.sql

@@ -0,0 +1,17 @@
+INSERT INTO workspace_agent_stats (
+	id,
+	created_at,
+	user_id,
+	agent_id,
+	workspace_id,
+	template_id,
+	connection_median_latency_ms
+) VALUES (
+	gen_random_uuid(),
+	NOW(),
+	gen_random_uuid(),
+	gen_random_uuid(),
+	gen_random_uuid(),
+	gen_random_uuid(),
+	1::bigint
+);

coderd/database/migrations/testdata/fixtures/000107_post_workspace_agent_stats_connection_latency.up.sql

@@ -0,0 +1,17 @@
+INSERT INTO workspace_agent_stats (
+	id,
+	created_at,
+	user_id,
+	agent_id,
+	workspace_id,
+	template_id,
+	connection_median_latency_ms
+) VALUES (
+	gen_random_uuid(),
+	NOW(),
+	gen_random_uuid(),
+	gen_random_uuid(),
+	gen_random_uuid(),
+	gen_random_uuid(),
+	0.5::float
+);