Add ROS2 bridge support for C++ nodes

Use the subscriber type for downcasting to ensure that the correct type is used. Also, store an unique ID per subscriber to differentiate subscriptions of same type after merging.

Metrics refactoring

the global meter.

Bump dora version to 0.3.2

Bump 0.3.2-rc2

This commit make it possible to check the logs as follows:

```bash
dora logs object_detection
```

If more than one dataflow is running, we will inquire for which dataflow to use.

Use forward slash as it is default way of defining ros2 topic

Test ros2 type info

Rework python ROS2 (de)serialization using parsed ROS2 messages directly

Co-authored-by: Haixuan Xavier Tao <tao.xavier@outlook.com>

Stream merging based on the cxx crate requires the bridge and the api to share an `ExternalEvents` type, which is only possible if the two bridge modules are defined in the same crate.

Required because arrow uses column-oriented data format, which requires all struct fields to have length 1.

Arrow has a special `BinaryArray` type for storing lists of variable-sized binary data efficiently. This type is equivalent to a `ListArray` of `PrimitiveArray<u8>`, but it is a different data type.

This commit updates the Python ROS2 serialization code to permit BinaryArray for all uint8 array or sequence fields.

Use ROS2 types as type info to ensure that serialization type matches exactly. This is necessary because the types need to match exactly, otherwise the serialization or deserialization will result in invalid data.

Using arrow schemas to specify the ROS2 message types does not work because not all ROS2 message types can be represented. For example, ROS2 serializes arrays with known length differently than sequences with dynamic length.

Bump h2 from 0.3.21 to 0.3.24

Bumps [h2](https://github.com/hyperium/h2) from 0.3.21 to 0.3.24.
- [Release notes](https://github.com/hyperium/h2/releases)
- [Changelog](https://github.com/hyperium/h2/blob/v0.3.24/CHANGELOG.md)
- [Commits](https://github.com/hyperium/h2/compare/v0.3.21...v0.3.24)

---
updated-dependencies:
- dependency-name: h2
  dependency-type: indirect
...

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