Make safetensors the default (#2120)
* Make safetensors default
* Rm location
* Actually flip flags
* Tests + update checkpointing
* Add to setup
* Start of tests with both safetensors and without
* Update tests to use both
* Remove from load state
* Explicit tip
* With suggestions
* Simplify, don't abstract. Need to bring back to deepspeed however
* Refactor to use consts
* Keep how it was
* Typo fix
