"before save" hooks provide "ctx.isNewInstance" whenever "ctx.instance"
is set. Possible values:
- true for all CREATE operations
- false for all UPDATE operations
- undefined for "prototype.save"
"after save" hooks provide "ctx.isNewInstance" whenever "ctx.instance"
is set. Possible values:
- true after all CREATE operations
- false after all UPDATE operations
- undefined after "updateOrCreate" and "save"
Note: both "updateOrCreate" and "prototype.updateAttributes"
don't provide `ctx.instance` to "before save" hooks, therefore
`ctx.isNewInstance` it not provided either.