refactor(image_diagnostics): fix namespace and directory structure

[technolojin]

Description

This PR puts headers in the autoware namespace.

Additional works

1. Align directory structure to follow the coding guidelines.

Related links

Part of: autowarefoundation/autoware#4569

How was this PR tested?

Tested in a local recompute environment.

# terminal 1
ros2 launch image_transport_decompressor image_transport_decompressor.launch.xml \
input_topic_name:=/sensing/camera/camera0/image_rect_color/compressed \
output_topic_name:=/sensing/camera/camera0/image_rect_color

# terminal 2
ros2 launch image_diagnostics image_diagnostics_node.launch.xml input_topic_name:=/sensing/camera/camera0/image_rect_color

# terminal 3: 
# play a bagfile contains '/sensing/camera/camera0/image_rect_color/compressed'

Notes for reviewers

None.

Interface changes

None.

Effects on system behavior

None.

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 28.44%. Comparing base (6d0247e) to head (7c1a6a8).
Report is 3 commits behind head on main.

Files	Patch %	Lines
...g/image_diagnostics/src/image_diagnostics_node.cpp	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7915      +/-   ##
==========================================
- Coverage   28.44%   28.44%   -0.01%     
==========================================
  Files        1591     1592       +1     
  Lines      116213   116221       +8     
  Branches    49613    49616       +3     
==========================================
  Hits        33059    33059              
- Misses      74141    74149       +8     
  Partials     9013     9013              

Flag	Coverage Δ		*Carryforward flag
differential	0.00% <0.00%> (?)
total	28.44% <ø> (+<0.01%)	⬆️	Carriedforward from 6d0247e

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[badai-nguyen]

LGTM