Replacing set_dir! string literal input by expression

[Kbz-8]

Just a small PR to be able to do things like :

let mut path = std::env::home_dir().expect("nah");
path.push(".local/share/myapp/");
dioxus_storage::set_dir!(path);

I am not sure about the dioxus versions bump tho.

[Kbz-8]

up !

[chunleng]

I am faced with the situation where Android doesn't work because the default is not writing to an accessible path. (Not sure if it's related to this issue)

This PR will definitely be a good workaround so that a correct path derived programatically can be included