[bug report] Dragula service is provided multiple times instead of as a singleton

[RGunning]

REQUIRED: Before filing a bug report

Change each [ ] to [x] when you have done it.

• My issue title starts with [bug report]
• I have read the README, especially the 'classic blunders' section, and the dragula docs.
• I have searched through the ng2-dragula issues for related problems, including closed issues.
• I have browsed through the issues labeled "future reference" for problems that have been solved before or have a known workaround.
• I am using the latest version of ng2-dragula.

Describe the bug (required)

With v3 of this library, the DragulaService is provided multiple times instead of just when importing DragulaModule.forRoot().

1. It is now providedIn: root https://github.com/valor-software/ng2-dragula/pull/1044/files#diff-845f2a393c0ade2f75831cff246267c8b1c96691d81d2d710c47f20eb14ef6d9R31
2. provided on import of the DragulaModule imports: [DragulaModule] https://github.com/valor-software/ng2-dragula/pull/1044/files#diff-77b8912947381f081ed7f9efbc418716a1dcdfac9c5ebc2d5e6539cad507878fR8
3. provided on calling DragulaModule.forRoot() imports: [DragulaModule.forRoot()]

As such it is easy to get inject the wrong instance of the DragulaService leading to incorrect behaviour. In my application I have a service (providedIn: Root) that injects the DragulaService. However, because it is providedIn root, since the v3 update it is now getting a different instance of the DragulaService to that injected into the DragulaDirective. As such calls of createGroup made in my root service are being ignored.

*** Expected:
importing DragulaModule does not provide an instance of the DragulaService and instead the DragulaService is either provided by providedIn: root or DragulaModule.forRoot(). My preferred solution would be to remove the forRoot and rely solely on providedIn: root, but this would be a breaking change.

Versions (required)

Please state which versions of the following packages you have installed:

• @angular/core: 14.2.12
• ng2-dragula: 3.2.0

[dino-laktasic]

I can confirm that I run into the same issue and it's definitely BUG. You should either provide DragulaService in root and remove it from providers list in DragulaModule and remove forRoot function or keep forRoot function and remove it from providers list in DragulaModule and remove providedIn from DragulaService service decorator. I tried fixes locally and they were working as expected.