Unified button and command naming convention

[psmyrek]

Suggested merge commit message (convention)

Other: Unified buttons, and commands naming convention. Old values are available as aliases. Read more about those changes in the Code style guide. Closes #8033.

Changes in toolbar buttons (before → after):

• imageUpload → uploadImage
• imageResize → resizeImage
• imageInsert → insertImage
• imageResize:* → resizeImage:*

Changes in command names:

• imageInsert → insertImage
• imageUpload → uploadImage
• imageResize → resizeImage
• forwardDelete → deleteForward
• todoListCheck → checkTodoList

MAJOR BREAKING CHANGE (list): The following module list/todolistcheckedcommand~TodoListCheckCommand has been moved to list/checktodolistcommand~CheckTodoListCommand.

MAJOR BREAKING CHANGE (image): The following modules have been moved (before → after)

• image/image/imageinsertcommand~ImageInsertCommand → image/image/insertimagecommand~InsertImageCommand
• image/imageresize/imageresizecommand~ImageResizeCommand → image/imageresize/resizeimagecommand~ResizeImageCommand
• image/imageupload/imageuploadcommand~ImageUploadCommand → image/imageupload/uploadimagecommand~UploadImageCommand

---

Additional information

ADR has been created: https://github.com/cksource/ckeditor5-internal/pull/426

[jodator]

Let's call it half-time review but for now I think that you could:

1. Fix the changes in the CHANGELOG.md files.
2. Update the docs (see comment).

After @Reinmar yay/no we should finish this PR if changes are needed.

[jodator]

Additionally, you can also rewrite the merge message as for now it is too mangled (all the changes in one line). If you don't have an idea about this we can think about that later, after all the changes. For start, I would split the massage for each plugin:

Other (image): Renamed UI buttons: imageInsert -> insertImage, imageUpload -> uploadImage, imageResize -> resizeImage. See #8033.
 
Other (list): Renamed todo list command naem todoListCheck -> checkTodoList. See #8033.

etc.

Also, we need to list all the breaking changes for the renamed classes, for instance:

MINOR BREAKING CHANGE (image): The `ImageInsert` command was renamed to `InsertImage`. See #8033.

[psmyrek]

After this half-time review all requested changes have been done:

• all CHANGELOG.md files have been reverted,
• list style in docs/framework/guides/contributing/code-style.md has been fixed,
• the merge message have been improved,
• all conflicts are resolved.

[Reinmar]

Oh, we haven't thought about that.

This will be another, big breaking change IMO. However, it might make sense to have this unified after all.

cc @Reinmar -> quick question - are we OK with unifying the configuration options as well?

Oh dear :D Yup, I didn't think about this.

So, I'm for changing it so it's consistent. If we touch anything, let's touch everything.

However, I'm leaning towards postponing this change til January's release. I have a feeling that we'll have a lot of breaking changes in it, or at least significant conceptual changes, so the rename would be less of a PITA there.

[pomek]

Since many buttons and commands are available as aliases, we don't introduce many minor/major breaking changes. Hence, I'd like to propose a little bit different merge massage:

Other: Unified buttons, and commands naming convention. Old values are available as aliases. Read more about those changes in the [Code style](TODO:URL_TO_OUR_DOCS) guide. Closes #8033.

Changes in toolbar buttons (before ⇒ after):

- `imageUpload` → `uploadImage`
- `imageResize` → `resizeImage`
- `imageInsert` → `insertImage`
- `imageResize:*` → `resizeImage:*`

Changes in command names:

- `imageInsert` → `insertImage`
- `imageUpload` → `uploadImage`
- `imageResize` → `resizeImage`
- `forwardDelete` → `deleteForward`
- `todoListCheck` → `checkTodoList`

MAJOR BREAKING CHANGE (list): The following module `list/todolistcheckedcommand~TodoListCheckCommand` has been moved to `list/checktodolistcommand~CheckTodoListCommand`.

MAJOR BREAKING CHANGE (image): The following modules have been moved (before → after) 

- `image/image/imageinsertcommand~ImageInsertCommand` → `image/image/insertimagecommand~InsertImageCommand`
- `image/imageresize/imageresizecommand~ImageResizeCommand` → `image/imageresize/resizeimagecommand~ResizeImageCommand`
- `image/imageupload/imageuploadcommand~ImageUploadCommand` → `image/imageupload/uploadimagecommand~UploadImageCommand`

@psmyrek, WDYT?

[psmyrek]

In toolbar buttons there is also imageInsert → insertImage change.

There is no such thing like todoListCheck button or checkTodoList button in CKE5.

In commands there is also imageResize → resizeImage change.

Renamed files:

packages/ckeditor5-image/src/image/imageinsertcommand.js   →   packages/ckeditor5-image/src/image/insertimagecommand.js
packages/ckeditor5-image/src/imageresize/imageresizecommand.js   →   packages/ckeditor5-image/src/imageresize/resizeimagecommand.js
packages/ckeditor5-image/src/imageupload/imageuploadcommand.js   →   packages/ckeditor5-image/src/imageupload/uploadimagecommand.js
packages/ckeditor5-image/tests/image/imageinsertcommand.js   →   packages/ckeditor5-image/tests/image/insertimagecommand.js
packages/ckeditor5-image/tests/imageresize/imageresizecommand.js   →   packages/ckeditor5-image/tests/imageresize/resizeimagecommand.js
packages/ckeditor5-image/tests/imageupload/imageuploadcommand.js   →   packages/ckeditor5-image/tests/imageupload/uploadimagecommand.js
packages/ckeditor5-list/src/todolistcheckcommand.js   →   packages/ckeditor5-list/src/checktodolistcommand.js
packages/ckeditor5-list/tests/todolistcheckcommand.js   →   packages/ckeditor5-list/tests/checktodolistcommand.js