Prevent Windows console window for yaaknode and yaakprotoc

Add new_xplatform_command() helper in yaak-common that creates a
tokio::process::Command with CREATE_NO_WINDOW flag set on Windows.

Also converts git commands to async for consistency.

crates/yaak-git/Cargo.toml

@@ -12,7 +12,9 @@ serde = { workspace = true, features = ["derive"] }
 serde_json = { workspace = true }
 serde_yaml = "0.9.34"
 thiserror = { workspace = true }
+tokio = { workspace = true, features = ["io-util"] }
 ts-rs = { workspace = true, features = ["chrono-impl", "serde-json-impl"] }
 url = "2"
+yaak-common = { workspace = true }
 yaak-models = { workspace = true }
 yaak-sync = { workspace = true }