expose utils from extism, particularly logging

very convenient to have a function like:
```zig
/// Logs format string to host, if log level is enabled.
pub fn log(level: comptime_int, comptime fmt: []const u8, args: anytype) !void {
const msg = try std.fmt.allocPrint(_plugin.allocator, fmt, args);
_plugin.log(@enumFromInt(level), msg);
}
```

Which is better if we have `pub` LogLevel in Extism zig-pdk, among other changes: https://github.com/extism/zig-pdk/issues/37