Separation of block interact disabling vs actual sneak/crouch

[dktapps]

Problem description

There are currently two functions of player sneaking:

1. to make the player appear to crouch & reduce their hitbox size
2. to disable block interactions when right-clicking on stuff

These two things are no longer coupled to the same thing. There are now 4 states for this:

State	Crouching	Disable block interaction	Note
Walking	false	false
Pressing shift while flying	false	true	#5792
Being in a 1.5 block space but not pressing shift	true	false	#5903
Pressing shift while walking	true	true

Proposed solution

There needs to be a separation of crouching from the player's desire to disable block interactions.

Unfortunately, this is difficult to do cleanly, as isSneaking is a Living function, meaning that it should refer to crouching, but the most common usages of sneaking in plugins will probably be to disable block interactions.

It's also difficult to choose a name for such a property. Player->disableBlockInteractions() is the best I can come up with, but I don't like it much.

Relates to #6544

Alternative solutions that don't require API changes