This pull request primarily involves changes to the project structure, specifically moving some files into an internal directory. The changes are intended to better organize the codebase. The most significant changes include updating the Makefile to reflect the new file locations, and updating import paths in cli_test.go and main.go to correctly reference the moved files.

Project structure changes:

• Makefile: Updated the bin/purl target to include the new location of the cli files in the internal directory.

Import path updates:

• internal/cli/cli_test.go: Updated import paths to reference the new location of the cli package in the internal directory.
• main.go: Updated import paths to reference the new location of the cli package in the internal directory.