Improve ResourceLimits interface to be more forward compatible

New interface allows users to generate ResourceLimits for interface so
that additions to TBuiltInResource do not break the ABI.

Users should use the glslang-default-resource-limits library and the
Public/ResourceLimits.h header. Similar changes have been made to the
C interface. Use Public/resource_limits_c.h.

Fixes #2822

gtests/Config.FromFile.cpp

@@ -32,7 +32,7 @@
 // ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 // POSSIBILITY OF SUCH DAMAGE.
 
-#include "StandAlone/ResourceLimits.h"
+#include "glslang/Public/ResourceLimits.h"
 #include "TestFixture.h"
 
 namespace glslangtest {
@@ -65,7 +65,7 @@ TEST_P(ConfigTest, FromFile)
         char* configChars = new char[len + 1];
         memcpy(configChars, configContents.data(), len);
         configChars[len] = 0;
-        glslang::DecodeResourceLimits(&resources, configChars);
+        DecodeResourceLimits(&resources, configChars);
         delete[] configChars;
     }