extension/dap: Add resolve_tcp_template function (#31010)

Extensions cannot look up available port themselves, hence the new API.
With this I'm able to port our Ruby implementation into an extension.

Release Notes:

- N/A

crates/dap/src/dap.rs

@@ -6,6 +6,8 @@ pub mod proto_conversions;
 mod registry;
 pub mod transport;
 
+use std::net::Ipv4Addr;
+
 pub use dap_types::*;
 pub use registry::{DapLocator, DapRegistry};
 pub use task::DebugRequest;
@@ -16,3 +18,19 @@ pub type StackFrameId = u64;
 
 #[cfg(any(test, feature = "test-support"))]
 pub use adapters::FakeAdapter;
+use task::TcpArgumentsTemplate;
+
+pub async fn configure_tcp_connection(
+    tcp_connection: TcpArgumentsTemplate,
+) -> anyhow::Result<(Ipv4Addr, u16, Option<u64>)> {
+    let host = tcp_connection.host();
+    let timeout = tcp_connection.timeout;
+
+    let port = if let Some(port) = tcp_connection.port {
+        port
+    } else {
+        transport::TcpTransport::port(&tcp_connection).await?
+    };
+
+    Ok((host, port, timeout))
+}