chore: refactor packages to make the project more structured

Description

Refactor packages to make the project more structured:

• move services to the internal package
• reformat imports
• remove unused functions

Related issue

Examples

Checklist

• the MR description has been reviewed
• this MR contains text changes and they have been reviewed OR there are no texts changes
• this MR contains GUI/CLI changes and they have been reviewed OR there are no GUI/CLI changes
• this MR contains API changes, specifications reflect those changes and they have been reviewed OR there are no API changes