feat: characterClass & characterRange

[mdjastrzebski]

Summary

test('"characterRange" base cases', () => {
  expect(buildPattern(characterRange('a', 'z'))).toBe('[a-z]');
  expect(buildPattern('x', characterRange('0', '9'))).toBe('x[0-9]');
  expect(buildPattern(characterRange('A', 'F'), 'x')).toBe('[A-F]x');
});

test('"characterClass" base cases', () => {
  expect(
    buildPattern(
      characterClass(characterRange('a', 'z'), characterRange('A', 'Z'))
    )
  ).toBe('[a-zA-Z]');
  expect(
    buildPattern(
       characterClass(characterRange('a', 'z'), anyOf('05')) 
    )
  ).toBe('[a-z05]');
  expect(
    buildPattern(
      characterClass(characterRange('a', 'z'), whitespace)
    )
  ).toBe('[a-z\\s]');
});```

### Test plan

Added tests.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (f620c06) 100.00% compared to head (88139c2) 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #29   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            9         9           
  Lines          127       142   +15     
  Branches        32        36    +4     
=========================================
+ Hits           127       142   +15     

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