Add include functionality and enhance file filtering with glob support

[yamadashy]

Thanks to @IsaacSante for the initial sketch of this feature!

What's New

1. Include Functionality: New option to specify files to include in the packed output using glob patterns.

CLI Usage

repopack --include "src/**/*.ts,**/*.md"

Note: Include and ignore patterns are comma-separated in the CLI.

Configuration Example

{
  "include": ["src/**/*.js", "**/*.md"],
  "ignore": {
    "customPatterns": ["*.test.js", "tmp/"]
  }
}

Key Points:

• New include patterns use glob syntax (e.g., **/*.md to match all markdown files in any directory)
• Existing ignore patterns continue to use .gitignore syntax (unchanged from previous versions)
• Combining include (glob) and ignore (.gitignore) patterns allows for powerful and familiar file selection

This enhancement adds glob-based include capabilities while maintaining the familiar .gitignore-style ignore patterns, giving users more control and flexibility in selecting files for packing.