feat: add optimization mode to vyper compiler

[charles-cooper]

this commit adds the --optimize flag to the vyper cli, which can take the values of "codesize" and "gas", and as an option in vyper json. it is to be used separately from the --no-optimize flag. this commit does not actually change any codegen, just adds the flag, threads it through the codebase so it is available once we want to start differentiating between the two modes, and sets up the test harness to test both modes.

What I did

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Commit message

this commit adds the `--optimize` flag to the vyper cli, and as an
option in vyper json. it is to be used separately from the
`--no-optimize` flag. this commit does not actually change codegen,
just adds the flag and threads it through the codebase so it is
available once we want to start differentiating between the two modes,
and sets up the test harness to test both modes.

it also makes the `optimize` and `evm-version` available as source code
pragmas, and adds an additional syntax for specifying the compiler
version (`#pragma version X.Y.Z`). if the CLI / JSON options conflict
with the source code pragmas, an exception is raised.

this commit also:
* bumps mypy - it was needed to bump to 0.940 to handle match/case, and
  discovered we could bump all the way to 0.98* without breaking
  anything
* removes evm_version from bitwise op tests - it was probably important
  when we supported pre-constantinople targets, which we don't anymore

Description for the changelog

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[codecov-commenter]

Codecov Report

Merging #3493 (11e678b) into master (29b02dd) will decrease coverage by 0.44%.
The diff coverage is 78.75%.

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@@            Coverage Diff             @@
##           master    #3493      +/-   ##
==========================================
- Coverage   89.37%   88.94%   -0.44%     
==========================================
  Files          84       84              
  Lines       10780    10882     +102     
  Branches     2457     2488      +31     
==========================================
+ Hits         9635     9679      +44     
- Misses        749      789      +40     
- Partials      396      414      +18     

Impacted Files	Coverage Δ
vyper/cli/vyper_compile.py	64.18% <28.57%> (-4.20%)	⬇️
vyper/cli/vyper_json.py	77.00% <62.50%> (-1.63%)	⬇️
vyper/ast/pre_parser.py	84.78% <68.42%> (-15.22%)	⬇️
vyper/compiler/__init__.py	88.88% <75.00%> (+0.79%)	⬆️
vyper/compiler/settings.py	88.23% <91.66%> (+8.23%)	⬆️
vyper/ast/__init__.py	100.00% <100.00%> (ø)
vyper/ast/utils.py	73.68% <100.00%> (+3.98%)	⬆️
vyper/compiler/phases.py	92.24% <100.00%> (+1.17%)	⬆️
vyper/evm/opcodes.py	100.00% <100.00%> (ø)
vyper/ir/compile_ir.py	93.76% <100.00%> (+0.01%)	⬆️

... and 4 files with indirect coverage changes

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[jacksonbinh4]

Correction and replace please