[bug] self.cpp_info.name breaks pkg-config for some packages

Defining self.cpp_info.name for a package changes (at least) two file names: cmake module FindFOO files, and pkg-config files. The problem is that in the wild, the name used for cmake module files and pkg-config files are not always identical, for example zlib has FindZLIB, but zlib.pc, and expat has FindEXPAT but expat.pc. recipes consuming these two packages via pkg-config are broken since these two recipes set self.cpp_info.name to uppercase, the workaround being to rename generated ZLIB.pc to zlib.pc and EXPAT.pc to expat.pc. If pkg-config files are always the lower-case version of corresponding findFOO cmake file, the simplest fix would be to modify pkg-config generator to use self.cpp_info.name.lower() instead of self.cpp_info.name. If not, a solution would be to make self.cpp_info.name a dictionary mapping generators to name.

[ericLemanissier]

The library name appears in the pkg-config file, and is currently in uppercase, but it does not seem to have an impact(renaming the file without modifying content solves the problem). According to https://people.freedesktop.org/~dbn/pkg-config-guide.html, name is A human-readable name for the library or package. This does not affect usage of the pkg-config tool, which uses the name of the .pc file.

[ericLemanissier]

This issue is not fixed by https://github.com/conan-io/conan/pull/5988 (eg freetype2 vs freetype is not a simple case change). EDIT: ok, I did not realize that this feature was tracked in https://github.com/conan-io/conan/issues/5993