add git_merge_commit_email into GitConfig

Signed-off-by: onur-ozkan <work@onurozkan.dev>

src/bootstrap/src/core/config/config.rs

@@ -2509,6 +2509,7 @@ impl Config {
         GitConfig {
             git_repository: &self.stage0_metadata.config.git_repository,
             nightly_branch: &self.stage0_metadata.config.nightly_branch,
+            git_merge_commit_email: &self.stage0_metadata.config.git_merge_commit_email,
         }
     }
 

src/tools/build_helper/src/git.rs

@@ -4,6 +4,7 @@ use std::process::{Command, Stdio};
 pub struct GitConfig<'a> {
     pub git_repository: &'a str,
     pub nightly_branch: &'a str,
+    pub git_merge_commit_email: &'a str,
 }
 
 /// Runs a command and returns the output