Jiaqiz/option to disable adapters & merge all lora layers
@HeyyyyyyG is this WIP? This PR is stale because it has been open for 14 days with no activity. Remove stale label or comment or update or this will be closed in 7 days. This PR is stale because it has been open for 14 days with no activity. Remove stale label or comment or update or this will be closed in 7 days. > LGTM! but i think we should merge #7988 before this one

Yes totally agree jenkins jenkins jenkins jenkins jenkins
# What does this PR do ?

Add a condition for all adapters modules: run through the adapter only when it is enabled

Add merging script for all lora layers.

# Usage
To enable or disable an adapter, we can use

```python
AdapterModuleMixin.set_enabled_adapters(name, enabled = True)
AdapterModuleMixin.set_enabled_adapters(name, enabled = False)
```
If ```name``` is not provided, then all adapters will be enabled/disabled. For example, one can disable all adapters using the following codes, which is equivalent to use only the base model.
```python
from nemo.core.classes.mixins.adapter_mixins import AdapterModuleMixin
for _, module in model.named_modules():
    if isinstance(module, AdapterModuleMixin) and module.is_adapter_available():
        module.set_enabled_adapters(enabled=False)
```

**PR Type**:
- [x] New Feature
- [ ] Bugfix
- [ ] Documentation

If you haven't finished some of the above items you can still open "Draft" PR.


## Who can review?

Anyone in the community is free to review the PR once the checks have passed. 
[Contributor guidelines](https://github.com/NVIDIA/NeMo/blob/main/CONTRIBUTING.md) contains specific people who can review PRs to various areas.

# Additional Information
* Related to # (issue)
