* [idl_parser] Validate `force_align` on all possible paths
- added validation of `force_align` for `Vector`.
- added assertion to `flatbuffers::PreAlign` method
These changes should resolve following oss-fuzz issues:
- 6275816289861632
- 5713529908887552
- 4761242994606080
* size_t problem on Mac
* Fix review notes