Fix(FileItemDefinition): use boost::regex in place of std::regex

Use boost::regex in place of std::regex to avoid crash on CentOS 7 inside FileItemDefinition.cxx. The change only affects FileItemDefinition class and address the following reported bug: aeva/aeva#261 (closed)

Implementation of stdlibc++ on gcc7 and later remain unstable due to recursive alogrithms leading to stack overflow crashes as documented here: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86164

The crash can be addressed by building with Ubuntu and gcc-9.3.0. Therefore, my initial hypothesis was that using devtoolset10 or devtoolset9 on centos would work similarly. However, the crash is not resolved by using either of devtoolset10 or devtoolset9.

Therefore, the only reliable way to address this bug is to temporarily use boost::regex in place of std::regex.