Misc v2 preparations (#2365)
* remove more tensorflow
* warning
* style
* correct
* Update optimum/commands/optimum_cli.py
* docs
* optimize cli startup time
* fix without breaking
* keep the speed
* add missing
* gard numpy import in import utils
* avoid importing diffusers simply because it is available and remove more tensorflow
* better error
* remove use_auth_auth
* add an all tasks constant
* rm old torch checks
* Update docs/source/exporters/overview.mdx
* fix
* add all tasks constant for export commands (use instead of TasksManager.get_all_tasks)
* Update optimum/utils/__init__.py
* fix
* speedup optimum-onnx cli
* fix
* fix typos
