Rename PreviewParameterProvider subclasses to the PreviewParam suffix

The `Provider` suffix reads as a dependency provider rather than as preview
data, and it collides with the real providers in the codebase — `StringProvider`,
`PickerProvider`, the login feature's `AccountProvider` — so the name says
nothing about which of the two a class is. `PreviewParam` says it.

195 classes are renamed, along with the 185 files named after them, the konsist
rule that enforces the convention, the presentation-class file templates and the
onboarding documentation.

This cannot be split. `Konsist.scopeFromProduction()` scans the whole project, so
flipping the assertion before every class has moved leaves the rule red, and a
rule that accepted either suffix during a transition would be exactly the kind of
compatibility layer this convention change is meant to remove.

Two judgement calls in the rule itself. The `name.endsWith("PreviewProvider")`
exclusion is dropped: its only job was to reject a redundant `Preview` before
`Provider`, and the new suffix already contains it; no class currently ends with
`PreviewProvider`, so removing it changes nothing today. And
`EditableAvatarViewUriProvider` is renamed rather than deleted from the exclusion
list even though no such class exists in this repository, since it presumably
comes from the modules overlaid for the enterprise build.

Nothing keyed off the old suffix: no snapshot filename contains a provider class
name, so no Paparazzi image changes, and the Kover variants match on `*Presenter`,
`*State` and `*ViewKt`, so coverage bounds are unaffected.

docs/_developer_onboarding.md

@@ -322,10 +322,10 @@ Example for a new feature called RoomDetails:
 4. Verify that the structure looks ok and click on Finish
 5. The modules api/impl should be created under `features/roomdetails` directory.
 6. Sync project with Gradle so the modules are recognized (no need to add them to settings.gradle).
-7. You can now add more Presentation classes (Events, State, StateProvider, View, Presenter) in the impl module with the `Template Presentation Classes`.
+7. You can now add more Presentation classes (Events, State, StatePreviewParam, View, Presenter) in the impl module with the `Template Presentation Classes`.
    To use it, just right click on the package where you want to generate classes, and click on `New` / `Template Presentation Classes`.
    Fill the text field with the base name of the classes: the generated files are `<BaseName>Event.kt`, `<BaseName>State.kt`,
-   `<BaseName>StateProvider.kt`, `<BaseName>Presenter.kt`, `<BaseName>Node.kt` and `<BaseName>View.kt`. For instance
+   `<BaseName>StatePreviewParam.kt`, `<BaseName>Presenter.kt`, `<BaseName>Node.kt` and `<BaseName>View.kt`. For instance
    `PreferencesRoot` in the `features/preferences/impl/root` package.
 
 
@@ -360,9 +360,9 @@ We have 3 tests frameworks in place, and this should be sufficient to guarantee
 - Maestro to test the global usage of the application. See the related [documentation](../.maestro/README.md).
 - Combination of [Showkase](https://github.com/airbnb/Showkase) and [Paparazzi](https://github.com/cashapp/paparazzi), to test UI pixel perfect. To add test,
   just add `@Preview` for the composable you are adding. See the related [documentation](screenshot_testing.md) and see in the template the
-  file [TemplateView.kt](../features/template/src/main/kotlin/io/element/android/features/template/TemplateView.kt). We create PreviewProvider to provide
+  file [TemplateView.kt](../features/template/src/main/kotlin/io/element/android/features/template/TemplateView.kt). We create PreviewParam classes to provide
   different states. See for instance the
-  file [TemplateStateProvider.kt](../features/template/src/main/kotlin/io/element/android/features/template/TemplateStateProvider.kt)
+  file [TemplateStatePreviewParam.kt](../features/template/src/main/kotlin/io/element/android/features/template/TemplateStatePreviewParam.kt)
 - Tests on presenter with [Molecule](https://github.com/cashapp/molecule) and [Turbine](https://github.com/cashapp/turbine). See in the template the class [TemplatePresenterTests](../features/template/src/test/kotlin/io/element/android/features/template/TemplatePresenterTests.kt).
 
 **Note** For now we want to avoid using class mocking (with library such as *mockk*), because this should be not necessary. We prefer to create Fake