C++: Add change notes

Author: jketema

cpp/ql/lib/change-notes/2025-01-07-config.md

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+---
+category: feature
+---
+* A new abstract class `ConfigurationTestFile` (`semmle.code.cpp.ConfigurationTestFile.ConfigurationTestFile`) was introduced, which represents files created to test the build configuration. A subclass `CmakeTryCompileFile` of `ConfigurationTestFile` was also introduced, which represents files created by CMake to test the build configuration.

cpp/ql/src/change-notes/2025-01-07-cmake.md

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+---
+category: minorAnalysis
+---
+* The `cpp/badly-bounded-write`, `cpp/equality-on-floats`, `cpp/short-global-name`, `cpp/static-buffer-overflow`, `cpp/too-few-arguments`, `cpp/useless-expression`, `cpp/world-writable-file-creation` queries no longer produce alerts on files created by CMake to test the build configuration.