Use PlayerAuthInputPacket::SNEAKING flag to test for sneaking

[Muqsit]

PlayerAuthInputPacket::SNEAKING flag covers the case where a player is sneaking during flight, something which START_SNEAKING & STOP_SNEAKING currently do not.

Related issues & PRs

• Fixes Sneaking while flying does not work #5792 - sneaking during flight would cause ghost block to appear when placing block against a chest
• Fixes Being in the 1.5 block space is interpreted as pressing the shift key #5903 - players could not place blocks when within the 1.5 block space (i.e., under a slab)

Changes

Behavioural changes

The server now correctly recognizes players who are sneaking while flying. Players are once again able to place blocks against interactable blocks (like chests and item frames) while in this state (without triggering block interaction). When under a slab (1.5 block space), players can place blocks and must explicitly sneak (on PC, by pressing shift key) to perform the usual sneak functionality.

Tests

// Debug chat message to test whether PlayerToggleSneakEvent is triggered as expected
// (i.e., no duplicate event calls, sneak event is initiated and terminated at proper times)
$plugin->getServer()->getPluginManager()->registerEvent(PlayerToggleSneakEvent::class, function(PlayerToggleSneakEvent $event) : void{
	$event->getPlayer()->sendMessage(gmdate("Y-m-d H:i:s.v") . ": sneaking=" . ($event->isSneaking() ? "yes" : "no"));
}, EventPriority::MONITOR, $plugin);

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[dktapps]

I'd imagine this probably fixes #5903 too.

I wouldn't be surprised if this kind of issue shows up with the other start/stop flags. Might be worth testing.

[Muqsit]

I'd imagine this probably fixes #5903 too.

I wouldn't be surprised if this kind of issue shows up with the other start/stop flags. Might be worth testing.

After some discussion and testing, the issue above is also addressed by this fix. However this PR trades the sneak functionality for a visual bug where players appear standing while they are under a slab/the 1.5 block space.

[dktapps]

Per internal discussion, sneaking needs to be split into "interact" sneaking (disables block interaction) vs "actual" sneaking (makes the player appear to sneak, reduces its collision box) to fully address this.