Add configurable Hermes build type option

Add HERMES_BUILD_TYPE CMake option to allow building Hermes in modes
other than Release. This is useful for debugging shermes crashes or
optimizer issues.

Usage:
  cmake -B build -DHERMES_BUILD_TYPE=Debug
  cmake -B build -DHERMES_BUILD_TYPE=RelWithDebInfo

Defaults to Release to maintain existing behavior and build performance.

Author: tmikov

README.md

@@ -1028,7 +1028,14 @@ Hermes is **automatically** cloned and built as part of the CMake configuration
   ```bash
   cmake -B build -DHERMES_GIT_TAG=abc123def
   ```
-- **Always Release mode**: Hermes always builds in Release for optimal performance
+- **Build type**: Set via `HERMES_BUILD_TYPE` (default: Release)
+  ```bash
+  # Build Hermes in Debug mode (useful for debugging shermes crashes)
+  cmake -B build -DHERMES_BUILD_TYPE=Debug
+
+  # Or RelWithDebInfo (optimized but with debug symbols)
+  cmake -B build -DHERMES_BUILD_TYPE=RelWithDebInfo
+  ```
 - **Per-config isolation**: Debug and Release builds get separate Hermes clones
 
 ### Building the Project

cmake/HermesExternal.cmake

@@ -77,14 +77,20 @@ else()
         CACHE STRING "Hermes git repository URL")
     set(HERMES_GIT_TAG "80359d48dbf0a108031d69c8a22bad180cfb4df3"
         CACHE STRING "Hermes git tag/commit/branch to build")
+    set(HERMES_BUILD_TYPE "Release"
+        CACHE STRING "Hermes build type (Release, Debug, RelWithDebInfo, MinSizeRel)")
 
     # Set Hermes paths - everything in build directory
     set(HERMES_SRC "${CMAKE_BINARY_DIR}/hermes-src")
     set(HERMES_BUILD "${CMAKE_BINARY_DIR}/hermes")
 
+    message(STATUS "Hermes git URL: ${HERMES_GIT_URL}")
+    message(STATUS "Hermes git tag: ${HERMES_GIT_TAG}")
+    message(STATUS "Hermes build type: ${HERMES_BUILD_TYPE}")
+
     # Configure Hermes build options
     set(HERMES_CMAKE_ARGS
-        -DCMAKE_BUILD_TYPE=Release
+        -DCMAKE_BUILD_TYPE=${HERMES_BUILD_TYPE}
         -DHERMES_ENABLE_TEST_SUITE=OFF
         -DHERMES_BUILD_APPLE_FRAMEWORK=OFF
         -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}