Make config names all use underscores

### Housekeeping

- [X] I am a maintainer of dbt-core

### Short description

dbt is not consistent with config names.

|dbt_project.yml|not dbt_project.yml|match|
| ------------- | ------------- | ------------- |
|pre-hook|pre_hook|:x:|
|post-hook|post_hook|:x:|
|semantic-models|semantic_models|:x:|
|full_refresh|full_refresh|:white_check_mark: |
|persist_docs|persist_docs|:white_check_mark: |

This may not be a complete list. Part of this ticket will be determining the list.

### Acceptance criteria

You can consistently use the underscore version of configs no matter what file you're in. The dash version is still allowed but throws a deprecation warning.

### Impact to Other Teams

Possibly adapters? Unlikely. Cloud config may be affected as well?

### Will backports be required?

Nope!

### Context

This is a papercut for users to have to know what format to enter a config name based on what file they are working in.