Fix raw call outsize

[iamdefinitelyahuman]

What I did

Do not return empty calldata in raw_call. Fixes #1976

How I did it

Compare RETURNDATASIZE to outsize and copy the smaller number of bytes to memory.

How to verify it

Run tests. I added / updated some cases. I also had to adjust some failing ones in test_wallet where the spirit of the test was that the call should succeed, but there was a check that it returned a non-empty value. Because of this change the value is now empty.

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[codecov-io]

Codecov Report

Merging #1977 into master will increase coverage by 0.58%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1977      +/-   ##
==========================================
+ Coverage   86.58%   87.17%   +0.58%     
==========================================
  Files          58       58              
  Lines        6636     6637       +1     
  Branches     1677     1677              
==========================================
+ Hits         5746     5786      +40     
+ Misses        569      536      -33     
+ Partials      321      315       -6     

Impacted Files	Coverage Δ
vyper/functions/functions.py	92.34% <100.00%> (+5.06%)	⬆️
vyper/ast/nodes.py	94.58% <0.00%> (+1.73%)	⬆️

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[fubuloubu]

@charles-cooper could you take a look at the proposed change and let us know if there's something we're missing about how raw_call works?

[charles-cooper]

I don't really get the purpose of the proposed change.

[charles-cooper]

Ok I think I understand it now. It's important for variable length return data. I think it is a good change, but using the name outsize is confusing because it suggests the length of the output will be that size. We could rename it to bufsize or max_outsize.

[iamdefinitelyahuman]

I like max_outsize, it's more more clear imo.

[charles-cooper]

Can't figure out how to approve from mobile. But, approved on my end.