Rename flatbuffer_serializer to *_mobile or *_full_jit (#82827)
The target named `flatbuffer_serializer` in fbcode has dependency from full jit and the one in xplat has dependency for mobile only. Rename them accordingly
```
flatbuffer_serializer in fbode -> flatbuffer_serializer_full_jit
flatbuffer_serializer in xplat -> flatbuffer_serializer_mobile
```
so it's more readable.
Differential Revision: [D38413369](https://our.internmc.facebook.com/intern/diff/D38413369/)
**NOTE FOR REVIEWERS**: This PR has internal Facebook specific changes or comments, please review them on [Phabricator](https://our.internmc.facebook.com/intern/diff/D38413369/)!
Differential Revision: [D38413369](https://our.internmc.facebook.com/intern/diff/D38413369)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/82827
Approved by: https://github.com/qihqi
