UI: update assembly icons to be consistent with main updates

[maxwxyz]

Consistency following #13865

• update assembly icons to be consistent with main updates
• add commands to menu/toolbar.

[maxwxyz]

Adjusted to match icon in main.

[chennes]

@PaddleStroke these features are ready to be out of "experimental stage"?

[PaddleStroke]

I would recommend that the features are left in experimental stage for about 2-3 months so that they can be tested by power users to make sure we iron out any outstanding issues.

And thanks for the icons update!

[FEA-eng]

I would recommend that the features are left in experimental stage for about 2-3 months so that they can be tested by power users to make sure we iron out any outstanding issues.

But this means that they will be available but not visible in the next stable release the whole time so most regular users (who often discover bugs thanks to extensive usage) won't have a chance to test them. Maybe at least add an easier way to activate them (like a preference) for those users?

[chennes]

Considering that Ondsel has these enabled in their recent release, it seems like that are stable enough for general use (or if they are not, then we do need to get them in front of users ASAP if we hope to have them in the 1.0 release)