refactor(orm): use naming strategy for computed field

[RomainLanz]

WARNING
This is a breaking change that must be documented.
To keep the previous behavior, users must manually set the name using the serializeAs option.

 class User extends BaseModel {
   @computed({ serializeAs: 'fullName' })
   declare fullName: string
 }

Hey! 👋🏻

This PR changes the way computed field works.

Beforehand, the computed field serialization wasn't using the naming strategy. Making the output inconsistent.
After this PR, the computed field will be serialized using the naming strategy (same as column field).

[RomainLanz]

Breaking tests are related to https://github.com/adonisjs/road-to-v6/discussions/41

[thetutlage]

Can you rebase with the latest commit? That way the breaking tests should pass

[RomainLanz]

Done 👍🏻