[Wasm] Rename wasm initialize function

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/compiler.kt

@@ -350,7 +350,7 @@ For more information see $d{uri("https://kotl.in/wasm_help/")}.
     
     wasmExports = wasmInstance.exports;
     if (runInitializer) {
-        wasmExports.__init();
+        wasmExports._initialize();
     }
 
     return { instance: wasmInstance,  exports: wasmExports };

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/ir2wasm/WasmCompiledModuleFragment.kt

@@ -178,14 +178,14 @@ class WasmCompiledModuleFragment(
             }
         }
 
-       val masterInitFunctionType = WasmFunctionType(emptyList(), emptyList())
-        val masterInitFunction = WasmFunction.Defined("__init", WasmSymbol(masterInitFunctionType))
+        val masterInitFunctionType = WasmFunctionType(emptyList(), emptyList())
+        val masterInitFunction = WasmFunction.Defined("_initialize", WasmSymbol(masterInitFunctionType))
         with(WasmIrExpressionBuilder(masterInitFunction.instructions)) {
             initFunctions.sortedBy { it.priority }.forEach {
                 buildCall(WasmSymbol(it.function), SourceLocation.NoLocation("Generated service code"))
             }
         }
-        exports += WasmExport.Function("__init", masterInitFunction)
+        exports += WasmExport.Function("_initialize", masterInitFunction)
 
         val typeInfoSize = currentDataSectionAddress
         val memorySizeInPages = (typeInfoSize / 65_536) + 1

compiler/testData/codegen/boxWasmJsInterop/imperativeWrapperUninitialised.kt

@@ -34,7 +34,7 @@ let { exports } = await instantiate(imports, /*runInitializer=*/false);
 if (exports.getInitialized() !== 0) {
     throw "Fail1"
 }
-exports.__init();
+exports._initialize();
 if (exports.getInitialized() !== 100) {
     throw "Fail2"
 }