Use LLVM new pass manager for wamrc (#978)

Use LLVM new pass manager for wamrc to replace the legacy pass manger,
so as to gain better performance and reduce the compilation time.
Reference links:
- https://llvm.org/docs/NewPassManager.html
- https://blog.llvm.org/posts/2021-03-26-the-new-pass-manager

And add an option to use the legacy pm mode when building wamrc:
cmake .. -DWAMR_BUILD_LLVM_LEGACY_PM=1

For JIT mode, keep it unchanged as it only runs several function passes and
using new pass manager will increase the compilation time.

And refactor the codes of applying LLVM passes.

core/config.h

@@ -98,6 +98,14 @@
 #define WASM_ENABLE_WAMR_COMPILER 0
 #endif
 
+#if WASM_ENABLE_WAMR_COMPILER != 0
+#ifndef WASM_ENABLE_LLVM_LEGACY_PM
+/* Whether to use LLVM legacy pass manager when building wamrc,
+   by default it is disabled and LLVM new pass manager is used */
+#define WASM_ENABLE_LLVM_LEGACY_PM 0
+#endif
+#endif
+
 #ifndef WASM_ENABLE_LIBC_BUILTIN
 #define WASM_ENABLE_LIBC_BUILTIN 0
 #endif