Add support for PlayStation platforms (#2562)

* Add new `CATCH_CONFIG` option for using `std::getenv`, because PS does not support env vars
* Add PS to platforms that have disabled posix signals.
* Small workaround for PS toolchain bug that prevents it from compiling `std::set` with lambda based comparator.

src/catch2/internal/catch_test_case_registry_impl.cpp

@@ -89,7 +89,7 @@ namespace Catch {
                                TestCaseInfo const* rhs ) {
             return *lhs < *rhs;
         };
-        std::set<TestCaseInfo const*, decltype(testInfoCmp)> seenTests(testInfoCmp);
+        std::set<TestCaseInfo const*, decltype(testInfoCmp) &> seenTests(testInfoCmp);
         for ( auto const& test : tests ) {
             const auto infoPtr = &test.getTestCaseInfo();
             const auto prev = seenTests.insert( infoPtr );