Calls value and stores the result in dynamically allocated memory instead
of taking a writer.
Caller owns returned memory.
pub fn valueAlloc(gpa: Allocator, v: anytype, options: Options) error
pub fn valueAlloc(gpa: Allocator, v: anytype, options: Options) error{OutOfMemory}![]u8 {
var aw: Writer.Allocating = .init(gpa);
defer aw.deinit();
value(v, options, &aw.writer) catch return error.OutOfMemory;
return aw.toOwnedSlice();
}