[WIP] Use references instead of values in CallBuilder API

[Robbepop]

• CallBuilder API
• CreateBuilder API

Seen improvements so far with the Delegator example contract:

Contract	Before PR	After PR	Reason
Accumulator	8.8 kB	8.8 kB	Expected since it does not use the CallBuilder API
Adder	13.0 kB	12.9 kB	Just minor improvement, need to find out why not more.
Subber	13.0 kB	12.9 kB	Same as with Adder.
Delegator	10.8 kB	10.5 kB	Minor improvements in WIP state. Expected to improve further.

Note, that the numbers do not yet include the full change so they are WIP.
Also I am sure we can do better in some places.

A problem will be how this will work out after #665 has been merged since the ink! codegen will be changed significantly through it and won't allow as easily to be adjusted than with the current codegen (which is unfortunate in this case, however, in general the new codegen is far superior).

[HCastano]

This is pretty stale (it was opened before the new codegen was merged), gonna close it

[xgreenx]

But that change still should be implemented because it will decrease significantly the size of contracts and performance with cross-contact calls

[HCastano]

It should, but right now there's nobody to implement it. It's still being tracked in #949, so we're not totally forgetting about it

[Robbepop]

To give a little bit of background why this staled: The implementation of this experimental PR just got waaaay too ugly which is never a good sign to further follow a road. So I stopped with this road and thought about another way of solving this instead. However, as it happens there were more important tasks to do at that time.
The wins with respect to file sizes were also pretty minor imo compared to the introduced ugliness and diff.