Validate string literals to only allow a subset of ASCII chars

[cburgdorf]

What was wrong?

As described in #329 we aren't yet validating string literals properly which causes our compiler to crash at the YUL stage (since YUL does perform that check)

How was it fixed?

Added an analyzer check + tests + spec update

[codecov-commenter]

Codecov Report

Merging #506 (fa481cf) into master (c8e58b5) will increase coverage by 0.01%.
The diff coverage is 100.00%.

❗ Current head fa481cf differs from pull request most recent head b784524. Consider uploading reports for the commit b784524 to get more accurate results

@@            Coverage Diff             @@
##           master     #506      +/-   ##
==========================================
+ Coverage   87.69%   87.71%   +0.01%     
==========================================
  Files          80       80              
  Lines        5276     5284       +8     
==========================================
+ Hits         4627     4635       +8     
  Misses        649      649              

Impacted Files	Coverage Δ
crates/analyzer/src/traversal/expressions.rs	90.90% <100.00%> (+0.13%)	⬆️
crates/yulgen/src/lib.rs	100.00% <100.00%> (ø)

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