Get the path to the Library folder (or in-memory DB) for all assets in a project

DumpAllAssetPaths.cs

using System.IO;
using System.Text;
using UnityEditor;
using UnityEditor.Experimental;
using UnityEngine;

public class DumpAllAssetPaths : MonoBehaviour
{
    [MenuItem("AssetDatabase/OutputAllLibraryPaths")]
    public static void OutputPathToAssets()
    {
        var findAssetsResult = AssetDatabase.GetAllAssetPaths();

        StringBuilder assetPathInfo = new StringBuilder();

        foreach (var assetPath in findAssetsResult)
        {
            var guidString = AssetDatabase.AssetPathToGUID(assetPath);
            var hash = AssetDatabaseExperimental.GetArtifactHash(guidString);

            AssetDatabaseExperimental.GetArtifactPaths(hash, out var paths);

            assetPathInfo.Append(AssetDatabase.GUIDToAssetPath(guidString));
            assetPathInfo.AppendLine();
            
            foreach (var curVirtualPath in paths)
            {
                //.info files are the asset previews which you can see as part
                //of the asset icon
                if(curVirtualPath.EndsWith(".info"))
                    continue;

                //The virtual path redirects somewhere, so we get the 
                //actual path on disk (or on the in memory database, accordingly)
                var curPath = Path.GetFullPath(curVirtualPath);
                assetPathInfo.Append("\t" + curPath);
                assetPathInfo.AppendLine();
            }
        }

        Debug.Log("Path info for all assets:\n"+assetPathInfo.ToString());
    }
}