refactor: remove once_cell dependency and use std::sync equivalents (#4185)

packages/mobile/Cargo.toml

@@ -15,7 +15,6 @@ dioxus-desktop = { workspace = true }
 dioxus-lib = { workspace = true }
 dioxus-cli-config = { workspace = true }
 libc = "0.2.170"
-once_cell = { workspace = true }
 
 [target.'cfg(target_os = "android")'.dependencies]
 jni = "0.21.1"