Accessing last modified time for directory handles

[TheCymaera]

For file handles, we can get the last modified time by calling FileSystemFileHandle.getFile().lastModifiedTime. This is not currently possible for directories.

A potential solution would be the addition of a stat() method for both file and directories handles. This would be helpful for multi-file editors like IDEs, which need to poll for changes. For example:

let oldTime = await dirHandle.stats().lastModifiedTime;
setInterval(async ()=>{
	const stats = await dirHandle.stats();

	if (oldTime < stats.lastModifiedTime) {
		oldTime = stats.lastModifiedTime;

		// infer changes and do stuff...
	}
},1000);

[mkruisselbrink]

Also related to #101 and #215, I agree that this is something we probable want.

[a-sully]

#101 has since been ported to whatwg/fs#12. Closing this issue in favor of that one