Add batch script support and fix minor issues

[megyerikenez]

Changes

This pull request introduces syntax highlighting support for Windows batch files to the project. The main addition is a new language definition for batch scripts, along with relevant tests to ensure proper detection and markup of batch syntax elements.

Batch language support:

• Added a new language definition file src/languages/batch.js for Windows batch files, supporting .bat, .batch, and .cmd extensions, with highlighting for built-in commands, operators, comments, strings, variables, and numbers.

Testing and validation:

• Added detection test file test/detect/batch/default.txt to verify that batch files are correctly identified by the language detector.
• Added markup test input test/markup/batch/default.txt and expected output test/markup/batch/default.expect.txt to validate syntax highlighting for various batch commands, comments, variables, and control structures. [1] [2]

Checklist

• Added markup tests, or they don't apply here because...
• Updated the changelog at CHANGES.md