GeezerVison

Adds TEST_PROPERTY(name, value) for C++ and TEST_PROPERTY_C(name, value)
for C, allowing test bodies to attach key-value metadata that appears in
JUnit XML output as <property> elements inside <testcase> blocks.

Properties flow through the existing UtestShell -> TestResult ->
TestOutput call chain, with JUnitTestOutput storing them on per-test-case
result nodes and emitting them when writing XML. The <properties> block
is only emitted when at least one property is present. Property names and
values are XML-encoded.

Adds a PropertySpyOutput that captures printTestProperty calls, and two
tests that drive the macros through ExecFunctionTestShell with a spy
result to verify the full routing chain from macro invocation to output.

Also adds the cpputest_test_property_c_caller helper in the C test file
to exercise TEST_PROPERTY_C from actual C code.

Fixes -Wmissing-prototypes error with clang-cl -Werror.

We don't need a macro that just forwards to a function.