fix: correct inner effect cleanup order

[YuanchengLi-Kevin]

Addresses issue #60 with owner's suggested fix.
TLDR: Clean up child effects and effect scopes before their parent reruns, and dispose dependencies in LIFO order.

New

• unlinkChildEffects(sub): a helper function from the owner's reactivity project (https://github.com/littensy/reactivity/blob/main/src/init.luau#L343)

• disposeAllDepsInReverse(sub): unlinks all dependencies in LIFO order (translated from this alien-signal commit (stackblitz/alien-signals@713a1c6)

• HAS_CHILD: a flag that marks whether a node's dependencies includes at least one child effect or effect scope (alien-signals translation)

Updated

• run(): check HAS_CHILD and unlink child effects before parent rerun
• stopEffect(): integrate disposeAllDepsInReverse()
• unwatched(): integrate disposeAllDepsInReverse()
• effect(): set HAS_CHILD flag
• effectScope(): set HAS_CHILD flag

Tests

• Unskipped and passed the two failing tests mentioned in the issue
• 3 new tests in effect.test translated from alien-signals (Passed)
• 3 new tests in effectScope.test translated from alien-signals (Passed)

[littensy]

My only concern is that I intended for Charm to use first-in-first-out effect cleanup order since that seems more intuitive, and reversing this order might be a breaking change.

I want to take a closer look at this when I'm able to and maybe propose changes to match reactivity's FIFO effect cleanup.