fix(usb_host_test): Fix cmake warninings about private include

[peter-marcisovsky]

Removing CMake warning when building target tests in host/usb/test/target_test

CMake Warning at /opt/esp/idf/tools/cmake/component_validation.cmake:86 (message):
Include directory '/__w/esp-usb/esp-usb/host/usb/private_include' belongs
to component usb but is being used by component common.  It is recommended
to define the component dependency for 'common' on the component usb, i.e.
'idf_component_register(...  REQUIRES usb)' in the CMakeLists.txt of
common, and specify the included directory as idf_component_register(...
INCLUDE_DIRS <dir relative to component>) in the CMakeLists.txt of
component usb.
Call Stack (most recent call first):
/opt/esp/idf/tools/cmake/component_validation.cmake:130 (__component_validation_check_include_dirs)
/opt/esp/idf/CMakeLists.txt:353 (__component_validation_run_checks)

Description

Adding USB component's private include using target_include_directories instead of INCLUDE_DIRS

Related

• Related to fix(build): Fix cmake warning about freertos component dependency tinyusb#77

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Checklist

Before submitting a Pull Request, please ensure the following:

• 🚨 This PR does not introduce breaking changes.
• All CI checks (GH Actions) pass.
• Documentation is updated as needed.
• Tests are updated or added as necessary.
• Code is well-commented, especially in complex areas.
• Git history is clean — commits are squashed to the minimum necessary.