Watch directories moved into the tree and report their content

Automatic subtree watching only reacted to `CREATE`, so a directory
moved in from elsewhere stayed unwatched. It is now handled like a
created one. Items that already exist in such a directory never
produce kernel events; they are reported with the same event kind
and `synthesized` set to `true`, so consumers can treat them as
newly appeared.

Sources/Inotify/DirectoryResolver.swift

@@ -23,6 +23,19 @@ public struct DirectoryResolver {
 		return resolved
 	}
 
+	/// The direct children of `directory`, without the excluded names.
+	static func entries(of directory: FilePath, excluding itemNames: Set<String> = []) async throws -> [(name: String, isDirectory: Bool)] {
+		let directoryHandle = try await fileManager.openDirectory(atPath: directory)
+		var entries: [(name: String, isDirectory: Bool)] = []
+		for try await childContent in directoryHandle.listContents() {
+			guard let name = childContent.path.lastComponent?.string else { continue }
+			guard !itemNames.contains(name) else { continue }
+			entries.append((name: name, isDirectory: childContent.type == .directory))
+		}
+		try await directoryHandle.close()
+		return entries
+	}
+
 	private static func withSubdirectories(at path: FilePath, recursive: Bool = false, body: (FilePath) async throws -> Void) async throws {
 		let directoryHandle = try await fileManager.openDirectory(atPath: path)
 		for try await childContent in directoryHandle.listContents() {