Merge topic 'refactor-cmDocumentation'

6e3e8827fa Refactor: `cmGlobalGeneratorFactory::GetDocumentation` returns entry
e99a4acbcd cmGlobalGeneratorFactory.h: Simplify returning default values
7daadd304f cmake.cxx: Simplify `cmake::AppendExtraGeneratorsDocumentation()`
df2047c2ac cpack.cxx: Optimize calls to `std::osteam::operator<<`
f6180485bb cpack.cxx: Eliminate redundant `if`
d7c183f35c cpack.cxx: Deduplicate "Generators" section creation code
9c06f0dd71 cmake.cxx: Move `static` functions to an anonymous namespace
69918b07e1 cmDocumentationEntry: Drop all user provided ctors for C++ >= 14
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Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: buildbot <buildbot@kitware.com>
Merge-request: !7605