Move to vendor namespace

[scottzach1]

Summary

Rename base pif package namespace to prevent potential conflicts

Details

Currently, the package uses the base pif namespace which can create conflicts with other packages such the pif package . This prevents a couple of potential issues:

1. Direct conflicts when projects depend on both python-injection-framework and pif
2. Silent conflicts through transitive dependencies where other project dependencies may rely on pif base namespace

Both scenarios can cause unpredictable behavior during pip installation as package precedence becomes arbitrary.