feat(t4-devkit): remove SensorChannel and replace it by str

[ktro2828]

Description

In order to support any kind of sensor channels, this PR removed SensorChannel class and replaced it by str.

How to review

Please confirm whether all variables that referred to SensorChannel previously are replaced by str.

How to test

Please check if tutorials work.

test data

test command

# Example
from t4_devkit import Tier4

t4 = Tier4("annotation", <DATA_ROOT>)
t4.render_scene(t4.scene[0].token)

Reference

Notes for reviewer

[Shin-kyoto]

LGTM

I confirmed that this PR works well. I checked with this dataset(TIER IV INTERNAL LINK)

Before this PR(commit hash: 8e46d0a6ee8968c9803317e7f3f7198b73d501f4)
Loading T4 tables in `annotation`...
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/tier4_perception_dataset_tools/pcd_type_updater/lib/tier4_perception_dataset/t4-devkit/t4_devkit/tier4.py", line 123, in __init__
    self.sensor: list[Sensor] = self.__load_table__(SchemaName.SENSOR)
  File "/tier4_perception_dataset_tools/pcd_type_updater/lib/tier4_perception_dataset/t4-devkit/t4_devkit/tier4.py", line 155, in __load_table__
    return build_schema(schema, filepath)
  File "/tier4_perception_dataset_tools/pcd_type_updater/lib/tier4_perception_dataset/t4-devkit/t4_devkit/schema/builder.py", line 24, in build_schema
    return SCHEMAS.build_from_json(name, filepath)
  File "/tier4_perception_dataset_tools/pcd_type_updater/lib/tier4_perception_dataset/t4-devkit/t4_devkit/schema/tables/registry.py", line 77, in build_from_json
    return schema.from_json(filepath)
  File "/tier4_perception_dataset_tools/pcd_type_updater/lib/tier4_perception_dataset/t4-devkit/t4_devkit/schema/tables/base.py", line 37, in from_json
    return [cls.from_dict(data) for data in records]
  File "/tier4_perception_dataset_tools/pcd_type_updater/lib/tier4_perception_dataset/t4-devkit/t4_devkit/schema/tables/base.py", line 37, in <listcomp>
    return [cls.from_dict(data) for data in records]
  File "/tier4_perception_dataset_tools/pcd_type_updater/lib/tier4_perception_dataset/t4-devkit/t4_devkit/schema/tables/sensor.py", line 109, in from_dict
    channel = SensorChannel(data["channel"])
  File "/usr/lib/python3.10/enum.py", line 385, in __call__
    return cls.__new__(cls, value)
  File "/usr/lib/python3.10/enum.py", line 710, in __new__
    raise ve_exc
ValueError: 'CAM_FRONT_LOWER' is not a valid SensorChannel

After this PR
Loading T4 tables in `annotation`...
Reverse indexing...
Done reverse indexing in 0.003 seconds.
======
8 attribute
8 calibrated_sensor
3 category
1601 ego_pose
51 instance
1 log
1 map
40 sample
1502 sample_annotation
1568 sample_data
3 visibility
8 sensor
1 scene
0 object_ann
0 surface_ann
0 keypoint
Done loading in 0.040 seconds.
======

NOTE: This PR introduces the following CONS:

• It becomes difficult to clearly manage sensors; any type of name will be permissible.

• This PR disables clearer information management such as quick modality checking. e.g. this code

• Managed as strings, which can lead to unintended inclusions and, being non-const, there's a possibility of modifications in code.