feat!: add ability to cancel pending workspace build (#18713)

Closes #17791 

This PR adds ability to cancel workspace builds that are in "pending"
status.

Breaking changes:
- CancelWorkspaceBuild method in codersdk now accepts an optional
request parameter

API:
- Added `expect_status` query parameter to the cancel workspace build
endpoint
- This parameter ensures the job hasn't changed state before canceling
- API returns `412 Precondition Failed` if the job is not in the
expected status
- Valid values: `running` or `pending`
- Wrapped the entire cancel method in a database transaction

UI:
- Added confirmation dialog to the `Cancel` button, since it's a
destructive operation

![image](https://github.com/user-attachments/assets/437aa5f4-5669-45b6-82a0-e46f277114bf)

![image](https://github.com/user-attachments/assets/423b5cb1-a4fb-4a10-933b-c1c73f4b838c)


- Enabled cancel action for pending workspaces (`expect_status=pending`
is sent if workspace is in pending status)

![image](https://github.com/user-attachments/assets/32d35ff1-12e6-4f7b-9f6c-fde9da9de6cf)

---------

Co-authored-by: Dean Sheather <dean@deansheather.com>

coderd/workspaces_test.go

@@ -3245,7 +3245,7 @@ func TestWorkspaceWatcher(t *testing.T) {
 	closeFunc.Close()
 	build := coderdtest.CreateWorkspaceBuild(t, client, workspace, database.WorkspaceTransitionStart)
 	wait("first is for the workspace build itself", nil)
-	err = client.CancelWorkspaceBuild(ctx, build.ID)
+	err = client.CancelWorkspaceBuild(ctx, build.ID, codersdk.CancelWorkspaceBuildParams{})
 	require.NoError(t, err)
 	wait("second is for the build cancel", nil)
 }