perf(files_reminders): Reduce db queries on propfind

[Pytal]

Summary

• Add caching for reminders
• Reduces database queries by n number of nodes in the directory per PROPFIND

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[icewind1991]

I'm pretty sure this can't throw?

[Pytal]

Interface says it can?

server/lib/public/Files/Node.php

Lines 93 to 101 in 6907b62

	/**
	* Get the internal file id for the file or folder
	*
	* @return int
	* @throws InvalidPathException
	* @throws NotFoundException
	* @since 6.0.0
	*/
	public function getId();