feat: Use 1-based indexing

[ianlewis]

Description:

Use one-based indexing for the line and column of lexemes as this is more user friendly (e.g. for error messages) and more intuitive.

Related Issues:

Fixes #81

Checklist:

• Review the CONTRIBUTING.md documentation.
• Add a reference to a related issue in the repository.
• Add a description of the changes proposed in the pull request.
• Add unit tests if applicable.
• Update documentation if applicable.
• Add a note in the CHANGELOG.md if applicable.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.57%. Comparing base (d7e80c4) to head (2029aab).

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #84      +/-   ##
==========================================
+ Coverage   91.14%   91.57%   +0.43%     
==========================================
  Files           3        3              
  Lines         463      463              
==========================================
+ Hits          422      424       +2     
+ Misses         30       28       -2     
  Partials       11       11              

Files with missing lines	Coverage Δ
lexer.go	86.49% <100.00%> (+0.84%)	⬆️