Add memory instance support apis (#3786)

Now that WAMR supports multiple memory instances, this PR adds some APIs
to access them in a standard way.

This involves moving some existing utility functions out from the
`WASM_ENABLE_MULTI_MODULE` blocks they were nested in, but multi-memory
and multi-module seem independent as far as I can tell so I assume that's okay.

APIs added:
```C
wasm_runtime_lookup_memory
wasm_runtime_get_default_memory
wasm_runtime_get_memory
wasm_memory_get_cur_page_count
wasm_memory_get_max_page_count
wasm_memory_get_bytes_per_page
wasm_memory_get_shared
wasm_memory_get_base_address
wasm_memory_enlarge
```

core/iwasm/include/wasm_export.h

@@ -120,6 +120,10 @@ typedef struct WASMModuleInstanceCommon *wasm_module_inst_t;
 typedef void WASMFunctionInstanceCommon;
 typedef WASMFunctionInstanceCommon *wasm_function_inst_t;
 
+/* Memory instance */
+struct WASMMemoryInstance;
+typedef struct WASMMemoryInstance *wasm_memory_inst_t;
+
 /* WASM section */
 typedef struct wasm_section_t {
     struct wasm_section_t *next;
@@ -939,6 +943,100 @@ WASM_RUNTIME_API_EXTERN void
 wasm_runtime_set_module_inst(wasm_exec_env_t exec_env,
                              const wasm_module_inst_t module_inst);
 
+/**
+ * @brief Lookup a memory instance by name
+ *
+ * @param module_inst The module instance
+ * @param name The name of the memory instance
+ *
+ * @return The memory instance if found, NULL otherwise
+ */
+WASM_RUNTIME_API_EXTERN wasm_memory_inst_t
+wasm_runtime_lookup_memory(const wasm_module_inst_t module_inst,
+                           const char *name);
+
+/**
+ * @brief Get the default memory instance
+ *
+ * @param module_inst The module instance
+ *
+ * @return The memory instance if found, NULL otherwise
+ */
+WASM_RUNTIME_API_EXTERN wasm_memory_inst_t
+wasm_runtime_get_default_memory(const wasm_module_inst_t module_inst);
+
+/**
+ * @brief Get a memory instance by index
+ *
+ * @param module_inst The module instance
+ * @param index The index of the memory instance
+ *
+ * @return The memory instance if found, NULL otherwise
+ */
+WASM_RUNTIME_API_EXTERN wasm_memory_inst_t
+wasm_runtime_get_memory(const wasm_module_inst_t module_inst, uint32_t index);
+
+/**
+ * @brief Get the current number of pages for a memory instance
+ *
+ * @param memory_inst The memory instance
+ *
+ * @return The current number of pages
+ */
+WASM_RUNTIME_API_EXTERN uint64_t
+wasm_memory_get_cur_page_count(const wasm_memory_inst_t memory_inst);
+
+/**
+ * @brief Get the maximum number of pages for a memory instance
+ *
+ * @param memory_inst The memory instance
+ *
+ * @return The maximum number of pages
+ */
+WASM_RUNTIME_API_EXTERN uint64_t
+wasm_memory_get_max_page_count(const wasm_memory_inst_t memory_inst);
+
+/**
+ * @brief Get the number of bytes per page for a memory instance
+ *
+ * @param memory_inst The memory instance
+ *
+ * @return The number of bytes per page
+ */
+WASM_RUNTIME_API_EXTERN uint64_t
+wasm_memory_get_bytes_per_page(const wasm_memory_inst_t memory_inst);
+
+/**
+ * @brief Get the shared status for a memory instance
+ *
+ * @param memory_inst The memory instance
+ *
+ * @return True if shared, false otherwise
+ */
+WASM_RUNTIME_API_EXTERN bool
+wasm_memory_get_shared(const wasm_memory_inst_t memory_inst);
+
+/**
+ * @brief Get the base address for a memory instance
+ *
+ * @param memory_inst The memory instance
+ *
+ * @return The base address on success, false otherwise
+ */
+WASM_RUNTIME_API_EXTERN void *
+wasm_memory_get_base_address(const wasm_memory_inst_t memory_inst);
+
+/**
+ * @brief Enlarge a memory instance by a number of pages
+ *
+ * @param memory_inst The memory instance
+ * @param inc_page_count The number of pages to add
+ *
+ * @return True if successful, false otherwise
+ */
+WASM_RUNTIME_API_EXTERN bool
+wasm_memory_enlarge(wasm_memory_inst_t memory_inst, uint64_t inc_page_count);
+
 /**
  * Call the given WASM function of a WASM module instance with
  * arguments (bytecode and AoT).