Unify ref-filter formats with other --pretty formats

Git has an old problem of duplicated implementations of some logic. For example, Git had at least 4 different implementations to format command output for different commands. The foremost aim of this project is to simplify codebase by getting rid of duplication of a similar logic and, as a result, simplify adding new functionality. The current task is to reuse ref-filter formatting logic in pretty to minimize code duplication and to have one unified interface to extract all needed data from the object and to print it properly.