Improve labels of "Call" page

[cmichi]

During workshops we had problems with people not intuitively understanding what "dry-run" means. I suggest the following:

• "Dry-run outcome" → Change label to "Preview" and directly below that "Result of dry-running the message on the contract."

[peetzweg]

@cmichi

Like this?

Or like this:

Personally, I find both a bit odd and think we are good without the Result of dry-running the message on the contract. line. How about we just put it into a information tooltip, similar too the labels of the Interact tab fields?

[statictype]

Dry-run is a relatively common term in Substrate, I'm not sure it's a good idea to adapt for a few users who don't know what it means. Surely, we'll encounter users who will be confused by "Preview" too 😛
If you think this change necessary @cmichi i suggest we go with @peetzweg's tooltip suggestion.