feat: Run Promise hooks around promise continuation jobs

[nabetti1720]

Closes #1740

Description of changes

This change emits JS_PROMISE_HOOK_BEFORE and JS_PROMISE_HOOK_AFTER around Promise reaction handler execution, passing the continuation Promise to both hooks.

When a Promise hook is installed, await handling creates a throwaway Promise capability for the continuation and associates it with the awaited Promise. When no hook is installed, await retains the existing allocation-free path.

Compatibility limitation: To preserve this optimization, the continuation Promise is created only if a hook is installed when the await reaction is scheduled. If a hook is installed afterward, BEFORE and AFTER still fire when the reaction runs, but their Promise argument may be undefined.

Tests cover hook invocation for .then() and await, including continuation Promise identity and its parent Promise.

Validation: cmake --build build --target api-test && ./build/api-test