[FEA] Allow configuring a subset of nodes in a certain mode.

まだ誰も着手していません。

Hi, first of all I want to say this is a great project to manage lifecycle nodes!

There'a a need to config the lifecycle state of only a subset of nodes in one mode, but config another subset of nodes in other modes.

Let's say, can the following config work? (Currently I don't need the extra parameter-based modes either)

#### SHM file

```yaml
# system modes example
---

actuation:
ros__parameters:
type: system
parts:
drive_base
left/manipulator
right/manipulator
modes:
__DEFAULT__:
drive_base: active.__DEFAULT__
left/manipulator: inactive.__DEFAULT__
right/manipulator: inactive.__DEFAULT__
LEFT:
# drive_base: active.__DEFAULT__
left/manipulator: active.__DEFAULT__
# right/manipulsator: inactive.__DEFAULT__
RIGHT:
# drive_base: active.__DEFAULT__
# left/manipulator: inactive.__DEFAULT__
right/manipulator: active.__DEFAULT__

left/manipulator:
ros__parameters:
type: node
modes:
__DEFAULT__:
ros__parameters:
max_torque: 0.1

drive_base:
ros__parameters:
type: node
modes:
__DEFAULT__:
ros__parameters:
max_speed: 0.1
controller: PID

right/manipulator:
ros__parameters:
type: node
modes:
__DEFAULT__:
ros__parameters:
max_torque: 0.11

```

EDIT, the step of reproduce has been updated @ralph-lange

#### step to reproduce

```sh
time ros2 service call /actuation/change_state lifecycle_msgs/ChangeState "{transition: {id: 1, label: configure}}"
time ros2 service call /actuation/change_state lifecycle_msgs/ChangeState "{transition: {id: 3, label: activate}}"
```

#### expected

the lefe manipulator should be in active

#### actual


Issue にある system-modes の YAML 設定から始め、/actuation/change_state に対する 2 つの ros2 サービス呼び出しを使って動作を再現します。部分的なモードマッピングが lifecycle nodes にどのように適用されるかを追跡します。モードが指定したノードのサブセットだけを設定し、他のノードの適切な状態を維持でき、提示された例で左マニピュレータが active に到達すれば完了です。

索引モデルが issue の本文から書いたものです。