feat: support stored values in `with!` and `update!` #939

Job	Run time
get-leptos-changed / Detect Source Change	6s
CI (integrations/axum) / Run ci (nightly)	16m 24s
CI (integrations/actix) / Run ci (nightly)	17m 54s
CI (integrations/utils) / Run ci (nightly)	15m 35s
CI (integrations/viz) / Run ci (nightly)	15m 51s
CI (leptos) / Run ci (nightly)	17m 56s
CI (leptos_config) / Run ci (nightly)	17m 52s
CI (leptos_dom) / Run ci (nightly)	17m 53s
CI (leptos_hot_reload) / Run ci (nightly)	14m 34s
CI (leptos_macro) / Run ci (nightly)	17m 54s
CI (leptos_server) / Run ci (nightly)	17m 53s
CI (leptos_reactive) / Run ci (nightly)	17m 37s
CI (meta) / Run ci (nightly)	16m 25s
CI (router) / Run ci (nightly)	17m 54s
CI (server_fn) / Run ci (nightly)	16m 13s
CI (server_fn_macro) / Run ci (nightly)	14m 30s
CI (server_fn/server_fn_macro_default) / Run ci (nightly)	14m 49s
	4h 27m 20s

Provide feedback