The beguiling, low-fi “Strawberry Mansion” is the kind of movie they don’t make anymore — not in the conventional, studio-era term of reassuring stories told and millions of hearts warmed, but as pure fantasy of consistently sprightly invention, special effects and animation elements with actual charm, and a spirit I can only describe as soulful. It’s 2035. The federal government employs “dream auditors” to make sure people are paying their taxes on their dream lives. If certain objects pop up in a dream, they’re assigned a monetary value. One such auditor, the fedora-topped Preble (co-directo…