Added AssertSubset and AssertNoSubset

[MarvinJWendt]

Closes #34

[codecov]

Codecov Report

Merging #73 (ef222af) into main (776d664) will decrease coverage by 0.44%.
The diff coverage is 60.00%.

@@            Coverage Diff             @@
##             main      #73      +/-   ##
==========================================
- Coverage   88.81%   88.37%   -0.45%     
==========================================
  Files          10       10              
  Lines         635      645      +10     
==========================================
+ Hits          564      570       +6     
- Misses         37       39       +2     
- Partials       34       36       +2     

Impacted Files	Coverage Δ
assert.go	97.13% <60.00%> (-1.39%)	⬇️

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