Add media embed and tables to all builds

[Reinmar]

• Add them to the builds themselves.
  • Find the space for them in the toolbars.
  • Change builds configuration.
• Update examples (and demos) of these builds to showcase the new features. (Consult @m-kr and @gok9ok about the content.)
• Check out the "Installation" sections of these features docs. There were notes like "This feature is not available in the builds..." which needs to be changed (take inspiration from guides of the features that are included).
• Update screenshots in https://ckeditor.com/docs/ckeditor5/latest/builds/guides/overview.html.

Did I forget about something?

[oleq]

Just for the record, I increased the priority of this issue

because as the toolbars grow (e.g. addition of the media-embed dropdown), this issue becomes visible even more.

[oleq]

We also need to start looking for solutions for #894

because if overcrowded toolbars in the classic/document do wrap to the next line, there's no such thing in the balloon editor. And this becomes a problem because no matter what, there's no way to position the balloon to fit the toolbar in the viewport in some situations because it's just too wide.

[gok9ok]

Update examples (and demos) of these builds to showcase the new features.

I can provide the content by midweek next week at best since I'm pretty overloaded right now. 😅 hope that's okay

[oleq]

@gok9ok Sounds good to me. @Reinmar, does it make sense for the roadmap?

---

I'll be able to update the build screenshots when

Find the space for them in the toolbars.

is approved by the reviewer.

The constellation is here #1254.

[Reinmar]

I merged everything. The remaining thing is updating the content.

[Reinmar]

Let's keep this open to not forget about updating the content of editor demos.

[oleq]

Just FYI #1247 (comment) has been addressed in https://github.com/ckeditor/ckeditor5-ui/issues/123

[oleq]

Updated the content of the build examples in b18b18c.