feat(coderd): implement task to app linking (#20237)

This change adds workspace build/agent/app linking to tasks and wires it
into `wsbuilder` and `provisionerdserver`.

Closes coder/internal#948
Closes coder/coder#20212
Closes coder/coder#19773

coderd/wsbuilder/wsbuilder.go

@@ -6,6 +6,7 @@ import (
 	"context"
 	"database/sql"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"net/http"
 	"time"
@@ -488,6 +489,21 @@ func (b *Builder) buildTx(authFunc func(action policy.Action, object rbac.Object
 			return BuildError{code, "insert workspace build", err}
 		}
 
+		// If this is a task workspace, link it to the latest workspace build.
+		if task, err := store.GetTaskByWorkspaceID(b.ctx, b.workspace.ID); err == nil {
+			_, err = store.UpsertTaskWorkspaceApp(b.ctx, database.UpsertTaskWorkspaceAppParams{
+				TaskID:               task.ID,
+				WorkspaceBuildNumber: buildNum,
+				WorkspaceAgentID:     uuid.NullUUID{}, // Updated by the provisioner upon job completion.
+				WorkspaceAppID:       uuid.NullUUID{}, // Updated by the provisioner upon job completion.
+			})
+			if err != nil {
+				return BuildError{http.StatusInternalServerError, "upsert task workspace app", err}
+			}
+		} else if !errors.Is(err, sql.ErrNoRows) {
+			return BuildError{http.StatusInternalServerError, "get task by workspace id", err}
+		}
+
 		err = store.InsertWorkspaceBuildParameters(b.ctx, database.InsertWorkspaceBuildParametersParams{
 			WorkspaceBuildID: workspaceBuildID,
 			Name:             names,