feat: add unsafe arithmetic ops

[charles-cooper]

What I did

introduce unsafe math ops for #2429

How I did it

add unsafe add/sub/mul/div builtins. for int types that are smaller than 256 bits, they perform wrapping arithmetic

How to verify it

check the tests

Commit message

(tbd)

Description for the changelog

Add unsafe_ arithmetic ops which don't use checked arithmetic

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[lgtm-com]

This pull request introduces 1 alert and fixes 1 when merging 606f151 into 82f44ee - view on LGTM.com

new alerts:

• 1 for Syntax error

fixed alerts:

• 1 for 'import *' may pollute namespace

[codecov-commenter]

Codecov Report

Merging #2629 (85ef71c) into master (3de52b3) will increase coverage by 0.00%.
The diff coverage is 86.95%.

@@           Coverage Diff           @@
##           master    #2629   +/-   ##
=======================================
  Coverage   86.29%   86.29%           
=======================================
  Files          91       91           
  Lines        9739     9787   +48     
  Branches     2466     2479   +13     
=======================================
+ Hits         8404     8446   +42     
- Misses        833      838    +5     
- Partials      502      503    +1     

Impacted Files	Coverage Δ
vyper/utils.py	85.71% <71.42%> (-1.43%)	⬇️
vyper/builtin_functions/functions.py	88.36% <93.54%> (+0.17%)	⬆️
vyper/codegen/expr.py	79.62% <100.00%> (+0.33%)	⬆️
vyper/cli/vyper_compile.py	68.14% <0.00%> (-0.56%)	⬇️

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[lgtm-com]

This pull request introduces 1 alert when merging ffce251 into e480e91 - view on LGTM.com

new alerts:

• 1 for Unused import

[lgtm-com]

This pull request introduces 1 alert and fixes 1 when merging d910d1b into e480e91 - view on LGTM.com

new alerts:

• 1 for Syntax error

fixed alerts:

• 1 for 'import *' may pollute namespace

[lgtm-com]

This pull request introduces 1 alert and fixes 1 when merging 7cb3379 into e480e91 - view on LGTM.com

new alerts:

• 1 for Syntax error

fixed alerts:

• 1 for 'import *' may pollute namespace

[lgtm-com]

This pull request introduces 2 alerts when merging 768abf9 into 3de52b3 - view on LGTM.com

new alerts:

• 2 for Unused import

[lgtm-com]

This pull request introduces 3 alerts when merging 748db64 into 3de52b3 - view on LGTM.com

new alerts:

• 3 for Unused import