WasmFS: Take canRead and canWrite parameters into account when setting directory mode

[paradust7]

Preloaded directories are always marked readable but not-writable:

emscripten/system/lib/wasmfs/wasmfs.cpp

Line 140 in 5312576

lockedParentDir.insertDirectory(childName, S_IRUGO | S_IXUGO);

But the call to createPath includes argument canWrite which can be true:

emscripten/src/library_wasmfs.js

Lines 65 to 68 in 5312576

	createPath: (parent, path, canRead, canWrite) => {
	// Cache file path directory names.
	wasmFS$preloadedDirs.push({parentPath: parent, childName: path});
	},