feat(coderd): add has_external_agent flag to template_versions and workspace_builds (#19285)

This pull request introduces support for external workspace management, allowing users to register and manage workspaces that are provisioned and managed outside of the Coder.

* Added has_external_agent field to workspace builds and template versions

coderd/database/queries/workspaces.sql

@@ -117,7 +117,8 @@ SELECT
 	latest_build.error as latest_build_error,
 	latest_build.transition as latest_build_transition,
 	latest_build.job_status as latest_build_status,
-	latest_build.has_ai_task as latest_build_has_ai_task
+	latest_build.has_ai_task as latest_build_has_ai_task,
+	latest_build.has_external_agent as latest_build_has_external_agent
 FROM
 	workspaces_expanded as workspaces
 JOIN
@@ -130,6 +131,7 @@ LEFT JOIN LATERAL (
 		workspace_builds.transition,
 		workspace_builds.template_version_id,
 		workspace_builds.has_ai_task,
+		workspace_builds.has_external_agent,
 		template_versions.name AS template_version_name,
 		provisioner_jobs.id AS provisioner_job_id,
 		provisioner_jobs.started_at,
@@ -370,6 +372,12 @@ WHERE
 			)) = (sqlc.narg('has_ai_task') :: boolean)
 		ELSE true
 	END
+	-- Filter by has_external_agent in latest build
+	AND CASE
+		WHEN sqlc.narg('has_external_agent') :: boolean IS NOT NULL THEN
+			latest_build.has_external_agent = sqlc.narg('has_external_agent') :: boolean
+		ELSE true
+	END
 	-- Authorize Filter clause will be injected below in GetAuthorizedWorkspaces
 	-- @authorize_filter
 ), filtered_workspaces_order AS (
@@ -439,7 +447,8 @@ WHERE
 		'', -- latest_build_error
 		'start'::workspace_transition, -- latest_build_transition
 		'unknown'::provisioner_job_status, -- latest_build_status
-		false -- latest_build_has_ai_task
+		false, -- latest_build_has_ai_task
+		false -- latest_build_has_external_agent
 	WHERE
 		@with_summary :: boolean = true
 ), total_count AS (