Size limit optimizations

[iamdefinitelyahuman]

What I did

Optimizations around size clamps.

How I did it

• When compiling for >= constantinople rules, handle sizelimits for address and bool using shr instead of a comparison to the in-memory size limit.
• During LLL optimization, check for unused size limit values. If any are found, remove the initial mstore operation to reduce the size of the bytecode.

How to verify it

Run tests.

Cute Animal Picture

[fubuloubu]

Really need to test this one across EVM versions. Does that happen?

[codecov-commenter]

Codecov Report

Merging #2175 into master will increase coverage by 0.01%.
The diff coverage is 91.42%.

@@            Coverage Diff             @@
##           master    #2175      +/-   ##
==========================================
+ Coverage   85.23%   85.25%   +0.01%     
==========================================
  Files          83       83              
  Lines        8336     8367      +31     
  Branches     2011     2019       +8     
==========================================
+ Hits         7105     7133      +28     
- Misses        731      732       +1     
- Partials      500      502       +2     

Impacted Files	Coverage Δ
vyper/optimizer.py	79.41% <88.46%> (+2.48%)	⬆️
vyper/parser/arg_clamps.py	100.00% <100.00%> (ø)

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