Enable gzip in modern content build

Update `scripts/build_all.sh` to pass `USE_GZIP=1` when building modern HTTP content, so the full build now generates gzip-compressed assets as part of the content step.

Author: vanvught

scripts/build_all.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 
 cd ../lib-remoteconfig/http/content
-make clean && make CONTENT=modern
+make clean && make CONTENT=modern USE_GZIP=1
 cd -
 
 cd ..