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/extension_api/src/extension_api.rs

@@ -22,6 +22,7 @@ pub use wit::{
     zed::extension::dap::{
         DebugAdapterBinary, DebugRequest, DebugTaskDefinition, StartDebuggingRequestArguments,
         StartDebuggingRequestArgumentsRequest, TcpArguments, TcpArgumentsTemplate,
+        resolve_tcp_template,
     },
     zed::extension::github::{
         GithubRelease, GithubReleaseAsset, GithubReleaseOptions, github_release_by_tag_name,

crates/extension_api/wit/since_v0.6.0/dap.wit

@@ -1,6 +1,9 @@
 interface dap {
     use common.{env-vars};
 
+    /// Resolves a specified TcpArgumentsTemplate into TcpArguments
+    resolve-tcp-template: func(template: tcp-arguments-template) -> result<tcp-arguments, string>;
+
     record launch-request {
         program: string,
         cwd: option<string>,