Improve isolation, execution limits and execution metrics by using Isolate (#683)

* Initial: use Isolate for isolation

* Continue: use Isolate for isolation

* Bug fixes

* timeout is wall-time for backward compatibility

* Documentation, signal names, reported time in ms

* Report memory usage in bytes

* Add privileged flags where needed

* Remove tmpfs

* Remove tmpfs

* Fix package installation

* Fix path, fix Zig: CRLF -> LF

docker-compose.dev.yaml

@@ -4,8 +4,7 @@ services:
     api:
         build: api
         container_name: piston_api
-        cap_add:
-            - CAP_SYS_ADMIN
+        privileged: true
         restart: always
         ports:
             - 2000:2000
@@ -13,8 +12,6 @@ services:
             - ./data/piston/packages:/piston/packages
         environment:
             - PISTON_REPO_URL=http://repo:8000/index
-        tmpfs:
-            - /piston/jobs:exec,uid=1000,gid=1000,mode=711
 
     repo: # Local testing of packages
         build: repo