## Description

Bring `ObjectChange` representation inline with `BalanceChange`,
`TransactionBlockEffects` etc. In particular objects are not loaded
unless explicitly requested.

This change also changes the `idCreated` and `idDeleted` fields to
always produce a value. They are marked as optional to give us
flexibility to change the schema in the future, not because they would
otherwise ever be `None`.

NB. I'm anticipating a follow-up change to not rely on the indexed
object change at all, and instead derive this data from effects, by
augmenting `TransactionEffectsAPI` to calculate this for us from raw
effects.

## Test Plan

```
sui-graphql-rpc$ cargo nextest run
sui-graphql-e2e-tests$ cargo nextest run -j 1 --features pg_integration
```

##  Stack

- #14929 
- #14930 
- #14934
- #14935 
- #14961 
- #14974
- #15013
- #15014
- #15015
- #15016
- #15018
- #15020
- #15021
- #15036 
- #15037 
- #15038 
- #15039 
- #15040
- #15041
- #15042 
- #15043
- #15044