Introduce Infer static analyzer to the CI pipeline

[henrybear327]

The Infer Docker Image in use is hosted on Docker Hub, which was built and pushed to sysprog21 by us since Infer's latest upstream release is very outdated at the time of writing.

The docker image size is around 470 MB, after numerous attempts to reduce its size from 3GB.

This PR also fixes issues reported by Infer. (The value written to &target_reg is never used.)