[resolves #89] Add a configuration to set stash page size when comparing changes for change set

[madappa-sharath]

Fixes #89

Proposed Changes

Stash compare changes rest api is paginated and only returns first 25 paths changed. In monorepos change set can be over 25 and the pipelines evaluated with partial change set can be inaccurate.

Provide a configuration to set higher page size limit.

Description

Added an environment config to specify page size and pass it onto GetStashFilesChanged if configured

Checklist

• [X] Read the CONTRIBUTING document.
• [X] Read the CODE OF CONDUCT document.
• [X] Add tests to cover changes.
• [X] Ensure your code follows the code style of this project.
• [X] Ensure CI and all other PR checks are green OR
  • [X] Code compiles correctly.
  • [X] Created tests which fail without the change (if possible).
  • [X] All new and existing tests passed.
• [X] Add your changes to Unreleased section of CHANGELOG.
• [X] Improve and update the README (if necessary).