feat: built-in operations `IncrementFrom` and `IncrementSet`

[nunomaduro]

TL DR: Update API Client types so both IncrementFrom and IncrementSet can be used for built-in operations.

The built-in operations IncrementFrom and IncrementSet guarantee that the update will be idempotent, as those operations will force the update to be rejected if applied more than once.

    index.partialUpdateObject({
      version: {
        _operation: 'IncrementFrom',
        value: 2,
      },
      objectID: 'myID',
    })
    .then(({ objectIDs }) => {
      console.log(objectIDs);
    });

Internal specs issue: #127

[nunomaduro]

This API Client is non-typed, therefore no action needs to be done here.