Main: use extras and fields in the foreign language specified in {_language=...} flag

[masatake]

These are mergeable parts in #3960.

I'm using the feature proposed in this pull request like this:

--langdef=KernelConfig{_foreignLanguage=Kconfig}

--_roledef-Kconfig.{config}=set,set in .config file
--_roledef-Kconfig.{config}=unset,unset in .config file

--map-KernelConfig=.config

--regex-KernelConfig=/^CONFIG_([^=]+)/\1/c/{_language=Kconfig}{_role=set}
--regex-KernelConfig=/^(CONFIG_[^=]+)/\1/c/{_language=Kconfig}{_role=set}{_extra=configPrefixed}{exclusive}

--regex-KernelConfig=/^\# CONFIG_([^ ]+) is not set/\1/c/{_language=Kconfig}{_role=unset}{exclusive}
--regex-KernelConfig=/^\# (CONFIG_[^ ]+) is not set/\1/c/{_language=Kconfig}{_role=unset}{_extra=configPrefixed}{exclusive}

The KernelConfig parser extracts "CONFIG_FOO=..." from foo.config.
The definition of CONFIG_FOO is in Kconfig. The Kconfig parser extracts the definition.

In foo.config, CONFIG_FOO= is set or unset. The KernelCOnfig parser can extract CONFIG_FOO as a reference tag of Kconfig language.

KernelConfig doesn't define its own kinds.

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 85.49%. Comparing base (a7b07d7) to head (500d0b6).

Files	Patch %	Lines
main/lregex.c	75.00%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4059   +/-   ##
=======================================
  Coverage   85.49%   85.49%           
=======================================
  Files         237      237           
  Lines       57036    57040    +4     
=======================================
+ Hits        48761    48765    +4     
  Misses       8275     8275           

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