Fix: Update deprecated actions and resolve subsequent build failures

- Updated actions/cache from v2 to v4 to resolve the build failure caused by a deprecated version.
- Updated actions/checkout from v2 to v4 as a proactive measure.

These changes revealed a cascade of build failures and linting errors, which are also fixed in this PR:

1.  The `clang-13` package is not available on `ubuntu-latest` runners. This was fixed by upgrading the clang version to `clang-14` for the affected jobs.
2.  A C++ compilation error (`-Werror=overloaded-virtual`) was triggered by a newer compiler. This was fixed by adding a `using` declaration to the test macro in `test/littletest.hpp`.
3. The `valgrind-dbg` package is not available on `ubuntu-latest`. This was fixed by removing it from the installation step.
4. macOS tests were failing to bind to port 8080. This was fixed by manually creating a socket with `SO_REUSEADDR` in the tests for macOS.
5. A large number of `cpplint` errors were revealed. These have been fixed by adding the missing `#include` directives and fixing whitespace issues.
6. A typo in a curl header include was fixed.

Author: google-labs-jules[bot]

test/integ/authentication.cpp

@@ -30,7 +30,7 @@
 #include <sys/socket.h>
 #endif
 
-#include <curl/curl.hh>
+#include <curl/curl.h>
 #include <memory>
 #include <string>