[Wasm] Loader improvements

- Output ES modules instead of plain files
- Support -Xwasm-launcher=d8 for d8 shell used in tests and benchmarks.
- Reuse launcher generation logic in CLI and box tests runners.
- Create separate output directory for each box since
  there are multiple output files generated for each test.
- Stop using absolute paths in generate JS files
  to simplify running generated code on different machine
- Remove ">>>" from println output


Merge-request: KT-MR-5729
Merged-by: Svyatoslav Kuzmich <svyatoslav.kuzmich@jetbrains.com>

libraries/stdlib/wasm/internal/kotlin/wasm/internal/ExternalWrapper.kt

@@ -139,8 +139,8 @@ internal fun anyToExternRef(x: Any): ExternalInterfaceType {
 }
 
 @JsFun("""(addr) => {
-    const mem16 = new Uint16Array(wasmInstance.exports.memory.buffer);
-    const mem32 = new Int32Array(wasmInstance.exports.memory.buffer);
+    const mem16 = new Uint16Array(wasmExports.memory.buffer);
+    const mem32 = new Int32Array(wasmExports.memory.buffer);
     const len = mem32[addr / 4];
     const str_start_addr = (addr + 4) / 2;
     const slice = mem16.slice(str_start_addr, str_start_addr + len);
@@ -163,7 +163,7 @@ internal fun convertJsStringToKotlinString(x: ExternalInterfaceType): String {
 //language=js
 @JsFun(
 """ (str, addr) => { 
-    const memory = new DataView(wasmInstance.exports.memory.buffer);
+    const memory = new DataView(wasmExports.memory.buffer);
     for (var i = 0; i < str.length; i++) {
         memory.setInt16(addr + i * 2, str.charCodeAt(i), true);
     }