Add namestyle for local variables in the outermost scope module_local_name_style

[AndreaWalchshoferSCCH]

This PR introduces a new namestyle module_local_name_style, which allows to specifiy a separate namestyle for local variables, that have no scope except the outermost one.
This allows to force a different name style whenever local variables are not within e.g. a function for easier distinction.

It is applied when local_name_style would be applied, but the variable is in the outermost scope. To not change the behavior in existing configurations, the configuration falls back onto the configuration of local_name_style in case the module_local_name_style is not explicitly configured.

This namestyle is independent of the existing module_name_style and require_module_name_style.

(Chinese documentation was translated from English using ChatGPT)

[AndreaWalchshoferSCCH]

Re-created PR for merge into original repo: CppCXY#177