Cleaning up ci

This merge request updates the GitLab CI configuration, improves the build and release process, and enhances the installation method for the repo-mapify tool. Key changes include:

1. Streamlining the CI pipeline by combining Ubuntu builds into a single Linux build.
2. Adding a new test job to verify the installation script.
3. Updating the release process to include an installation script and simplify binary downloads.
4. Updating the README with new installation instructions, including a quick install script.
5. Adding an installation script (install.sh) that automatically detects the user's OS and architecture, downloads the appropriate binary, and installs it in a suitable location.

These changes aim to make the tool easier to install and use across different platforms, while also improving the development and release workflow.