Add VE-Type argument

[Alexis-BX]

Add an argument that can be passed to deepspeed in the pretrain and finetune launch scripts. This argument will be used to pick which VE class to use.
Types needed: CLIP, OCLIP, timm
For OCLIP models it is also necessary to pass the config of the VE to enable local models (see load_model in open_clip.py), and if the model uses Timm in OpenClip
Working directory: robin/model/multimodal_encoder/
Additional objectives:

1. remove the encoder_info.py file
2. remove all conditions with model_name == ...