Upgrade Zig to 0.11.0

[A1Liu]

So many things were changed and none of them were expected

• The whole Allocator interface is now changed again as of std.mem.Allocator: allow shrink to fail
• Something changed with all the options as of std: collect all options under one namespace
• File imports are borked as of AstGen: detect and error on files included in multiple packages
• WASM symbols that say "export" no longer actually export by default as of WebAssembly: remove unconditional --allow-undefined flag