feat: Implement experiment gated CRUD for workspace proxies (#6928)

* feat: Implement basic moon crud
* chore: Implement enterprise endpoints for moons

coderd/database/migrations/000114_workspace_proxy.up.sql

@@ -0,0 +1,23 @@
+BEGIN;
+CREATE TABLE workspace_proxies (
+    id uuid NOT NULL,
+    name text NOT NULL,
+    display_name text NOT NULL,
+    icon text NOT NULL,
+    url text NOT NULL,
+	wildcard_hostname text NOT NULL,
+	created_at timestamp with time zone NOT NULL,
+	updated_at timestamp with time zone NOT NULL,
+	deleted boolean NOT NULL,
+
+    PRIMARY KEY (id)
+);
+
+COMMENT ON COLUMN workspace_proxies.url IS 'Full url including scheme of the proxy api url: https://us.example.com';
+COMMENT ON COLUMN workspace_proxies.wildcard_hostname IS 'Hostname with the wildcard for subdomain based app hosting: *.us.example.com';
+
+
+-- Enforces no active proxies have the same name.
+CREATE UNIQUE INDEX ON workspace_proxies (name) WHERE deleted = FALSE;
+
+COMMIT;