Use theme spaces for DropdownMenu gutter

[Calvein]

Rather than forcing the user to set a number for the number, I've added the spaces coming from the theme in addition.

@Jademhm & @aurelienalletru we have a spacing (the gutter) of 10 between the trigger & the dropdown by default, would you rather have 8 (sm) or 12 (md)?

[github-actions]

👀 Visit Preview

[theo-mesnil]

I think we don't want to add another value from theme, 10px is the spacing from the specs by default and we need all to use it to be consistent

[theo-mesnil]

@Calvein but i think we need to get default space from theme and not with a number

[Calvein]

@Calvein but i think we need to get default space from theme and not with a number

That was a suggestion but I didn't look at the specs about the 10px, I thought it was an old value that we kept 👀

I've added the gutter to the theme and I added it as a default in fd3e382

[theo-mesnil]

@Calvein i check the figma and it's now xs

[theo-mesnil]

@Calvein need rebase :)

[Calvein]

All good 🚀