Make version of Emscripten SDK configurable

Author: 0xEAB

templates/opend/emscripten/install-emsdk.containerfile

@@ -7,6 +7,6 @@ RUN tar -xf emsdk.tar.gz -C emsdk --strip-components=1
 {{< opend/emscripten/install-emsdk-dependencies.containerfile }}
 
 ##### Install SDK
-RUN /opt/build/emsdk/emsdk install latest
-RUN /opt/build/emsdk/emsdk activate latest
+RUN /opt/build/emsdk/emsdk install {{ $EMSDK_VERSION ?? 'latest' }}
+RUN /opt/build/emsdk/emsdk activate {{ $EMSDK_VERSION ?? 'latest' }}