Add initial provider for PHP to scan a codebase

[erbesharat]

This issue aims to create a starting point for implementing PHP support into our codebase.

The most basic feature we require when implementing a new language support is scanning a code base.

According to the implementation we have for NodeJS codebase scan, we can mimic the same behavior in a new language.

Some languages might have different logics for importing modules or their global context, so make sure to discuss the implementation you have in mind, prior to its implementation so we can come up with follow-up issues.