Add workload through leveraging OCI images to run on CI
Based on the workload used in https://github.com/sysprog21/elfuse/issues/224 and the newly merged OCI image capability, python, node, go, jvm, c, and redis images are pulled and run on CI for all PR, making sure that elfuse is able to execute common workload normally after changes.
Summary by cubic
Adds oci-runtime CI lanes that run elfuse against real runtimes (python, node, go, jvm, c, redis) on OCI images, so common workloads are exercised on every PR and push. The smoke helper functions move to a shared oci-lib.sh, and each lane is documented in docs/oci-images.md and docs/usage.md.
The python lane covers threaded SQLite writers, filesystem walks, subprocesses, and Unix sockets longer than the host's sun_path. The node and redis lanes expose server guests to the host or a second guest, and the go lane sets GODEBUG=asyncpreemptoff=1 so async preemption cannot inject signals into the vCPU path.