Solve Obsidian Workspaces interaction needs with files and directories

Obsidian Workpaces searches files with a specific patterns in a directory
to list them or read them as filesystem database.

Add convenient utilities method to File and Directory to support those needs.

Test Plan: Tested with Obsidian Workspaces code in D4185.

Differential Revision: https://devcentral.nasqueron.org/D4186