Add support for APOLLO optimizer

[ddaspit]

The APOLLO optimizer has been added to Huggingface Transformers. APOLLO is a memory-efficient optimizer with similar performance to AdamW. We will need to add a dependency on the apollo-torch package. APOLLO can be enabled by setting the optim to apollo_adamw. We will also need to automatically set optim_target_modules based on the currently selected model. For more information, see the documentation.