Shared heap enhancements for Interpreter and AOT (#4400)

Propose two enhancements:

- Shared heap created from preallocated memory buffer: The user can create a shared heap from a pre-allocated buffer and see that memory region as one large chunk; there's no need to dynamically manage it(malloc/free). The user needs to make sure the native address and size of that memory region are valid.
- Introduce shared heap chain: The user can create a shared heap chain, from the wasm app point of view, it's still a continuous memory region in wasm app's point of view while in the native it can consist of multiple shared heaps (each of which is a continuous memory region). For example, one 500MB shared heap 1 and one 500 MB shared heap 2 form a chain, in Wasm's point of view, it's one 1GB shared heap.

After these enhancements, the data sharing between wasm apps, and between hosts can be more efficient and flexible. Admittedly shared heap management can be more complex for users, but it's similar to the zero-overhead principle. No overhead will be imposed for the users who don't use the shared heap enhancement or don't use the shared heap at all.

core/iwasm/compilation/aot_llvm.h

@@ -254,8 +254,12 @@ typedef struct AOTFuncContext {
     bool mem_space_unchanged;
     AOTCheckedAddrList checked_addr_list;
 
+    /* The last accessed shared heap info */
     LLVMValueRef shared_heap_base_addr_adj;
     LLVMValueRef shared_heap_start_off;
+    LLVMValueRef shared_heap_end_off;
+    /* The start offset of the head of shared heap chain */
+    LLVMValueRef shared_heap_head_start_off;
 
     LLVMBasicBlockRef got_exception_block;
     LLVMBasicBlockRef func_return_block;
@@ -486,6 +490,7 @@ typedef struct AOTCompContext {
     bool enable_gc;
 
     bool enable_shared_heap;
+    bool enable_shared_chain;
 
     uint32 opt_level;
     uint32 size_level;