feat(entproto): add support for custom package in `gen-entgrpc`

[marcozac]

This PR allows you to generate services when database assets are not generated in the schema parent directory and/or the package name is not ent.

Currently entc.LoadGraph uses an empty configuration, setting the Package value to the schema parent directory name by default.

It may lead to broken imports if the database assets are generated by providing a different Target to entc.Generate.

For example, if the schema directory is in ent/schema and the entc.Generate target is db as in the diagram below, entpb_user_service.go will try to import the User entity from "project/ent/user" instead of "project/db/user".

project
├───ent
│   └───schema
│       │   user.go
│       │   ...
└───db
    └───user
    │   │   user.go
    │   │   ...
    └───proto
        └───entpb
        │   │   entpb.proto
        │   │   entpb_user_service.go
        │   │   ...
        │   runtime.go
        │   ...

---

Using the go_package flag it is possible to pass a custom Package value to entc.LoadGraph configuration and in the templates, hard-coded ent.* are accordingly replaced with $entPackage variable to allow for different package names.

[rotemtam]

Hey @marcozac !

Thanks for the contribution. Could you please elaborate more on this change, why/when is it needed?

[marcozac]

Hey @marcozac !

Thanks for the contribution. Could you please elaborate more on this change, why/when is it needed?

Hi @rotemtam, sure!

Sorry, I opened this draft PR before realising that it was almost 2:00 am 😅.

I'll update it shortly. I'm writing an example and a test just now!

[hartmamt]

This would be really helpful for us as well. We use the target flag to generate ent into a generated folder. That works fine for ent and for entgql, but entproto doesn't have a way to handle it. We ended up having to write a script that rewrote some of the imports to include our target directory.