chore(.clang-tidy): fix settings of readability-identifier-naming

[kenji-miyake]

Description

The settings that I added in #2763 was a bit wrong.

• Use _ for PrivateMemberSuffix.
  Google C++ Style Guide says Data members of classes, both static and non-static, are named like ordinary nonmember variables, but with a trailing underscore.
• Use lower_case with prefix g_ for GlobalConstantCase.
  ROS 2 Docs says For global variables use lowercase with underscores prefixed with g_.
• Use lower_case for ConstexprVariableCase.
  For these lines.

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[isamu-takagi]

Use lower_case for ConstexprVariableCase.

For message type, the rosidl disallows the use of constant names other than UPPER_CASE. Can this pass the check? And the google guideline says to use kConstatntName. So is this Autoware's own rule?

[kenji-miyake]

For message type, the rosidl disallows the use of constant names other than UPPER_CASE. Can this pass the check?

I've confirmed this behavior. clang-tidy didn't raise warnings unless we intentionally add -system-headers and -header-fileter=.*.
Since it only affects to user code, I think it's acceptable.

And the google guideline says to use kConstatntName. So is this Autoware's own rule?

Yes. I personally think it's acceptable considering one of the rationales consistency across languages in ROS 2 Docs.

As you write here, it is natural that we use lower_case for constexpr variables.

@isamu-takagi What do you think?

[isamu-takagi]

LGTM

[xmfcx]

It'll be good to have this finally enforced.