feat: Unify update/install/open and use YaruSplitButton

[spydon]

Screencast from 2024-10-14 10-50-44.webm

• Alignment of some context menues are still a bit off when it has extra space.
• We shouldn't merge this until a new yaru version is released.

[spydon]

Great work, LGTM! Could we wait until a new yaru version is released before merging this, to not depend on yaru's main branch?

That's the plan, we're doing the Yaru release now :)