Align Dropdown and DropdownMenu styles

[youknowriad]

Closes #8559
While working on #18624 I notice that if I use Dropdown or DropdownMenu, the styling of the DropdownToggle is different. This PR tries to address that by:

• Removing specific styles from DropdownMenu and just relying on the default styles of IconButton
• In addition to that I automatically applied inline-block to all Dropdown wrappers, i think it makes sense IMO (duplicate of Add support for dropdown container to be inline-block (#8559) #16491). this allows the popover to be positioned properly.

The downside here is that the specific styles for the Toggle in DropdownMenu were specifically targetted to match the styling of ToolbarButton (block toolbars) which means the size of the regular buttons and the dropdowns (hover) is not consistent now. My thinking at the moment is that we should fix this by removing the specific styles for ToobarButton and instead make sure any IconButton (ToolbarButton or not) inside Toolbar component should be adapted (hover styles with a smaller size).

I decided to leave the toolbar hover style fix for a separate PR but if you think the breakage in the current PR is severe enough, I'm happy to do everything in the same PR. I preferred not including here to keep the size of the PR smallish.

I also added a temporary story to the Dropdown component where we show both a DropdownMenu and a Dropdown in the same canvas to be able to compare them.

[ItsJonQ]

Thanks for fixing this! Changing the display of the div makes sense. Can confirm it's working in Storybook 👍

[ItsJonQ]

@youknowriad Tested in Docker + Storybook, and it's working as expected. Awesome job 🚀 .

I decided to leave the toolbar hover style fix for a separate...

I agree 👍

[youknowriad]

When trying to work on the toolbar buttons style alignments, I noticed that it basically comes down to remove styles from the ToolbarButton component, so I just went ahead and did it here.

The hover style is not consistent but bigger than it was before. It could be considered a very small visual regression but I think consistency wins here and if we were to restore the smaller hover style, we should restore it for all components consistently.

[jasmussen]

This is what I see when running this branch:

If that's also what you see, then 👍 👍

[gziolo]

I noticed that this change created regression for toolbar buttons:

When they are toggled they no longer change their visual appearance. This is how it worked before 7.0:

Filed in #18825.