feat(router): add opt-in mimalloc feature (#141)

Co-authored-by: Sanchith Hegde <22217505+SanchithHegde@users.noreply.github.com>

crates/router/src/lib.rs

@@ -50,6 +50,10 @@ use crate::{
     core::errors::{self, BachResult},
 };
 
+#[cfg(feature = "mimalloc")]
+#[global_allocator]
+static ALLOC: mimalloc::MiMalloc = mimalloc::MiMalloc;
+
 /// Header Constants
 pub mod headers {
     pub const X_API_KEY: &str = "X-API-KEY";