Import accesskit and raise minimum Rust version to match it

Cargo.toml

@@ -32,14 +32,19 @@ edition = "2021"
 description = "Top level crate for Blitz"
 license = "MIT OR Apache-2.0"
 keywords = ["dom", "ui", "gui", "react", "wasm"]
-rust-version = "1.60.0"
+rust-version = "1.70.0"
 publish = false
 
+[features]
+accesskit = ["dep:accesskit"]
+default = ["accesskit"]
+
 [profile.dev.package."*"]
 opt-level = 2
 
 # Need to force specific versions of these dependencies
 [dependencies]
+accesskit = { version = "0.12.2", optional = true }
 # webrender = "0.61.0"
 euclid = { version = "0.22", features = ["serde"] }
 # mozbuild = "0.1.0"