Running Composer commands - revert patched files (when working on Drupal core)

[shaal]

Describe the bug

After starting DrupalPod instance, based on a Drupal core issue -
running a Composer command (ie. ddev composer require drupal/gin) - resets web/index.php.

To Reproduce

Start DrupalPod based on Drupal core issue, example -
https://gitpod.io/#DP_PROJECT_NAME=drupal,DP_ISSUE_FORK=,DP_ISSUE_BRANCH=,DP_PROJECT_TYPE=project_core,DP_MODULE_VERSION=9.4.x,DP_CORE_VERSION=9.3.x,DP_PATCH_FILE=https%3A%2F%2Fwww.drupal.org%2Ffiles%2Fissues%2F2020-10-19%2F3114813-21.patch,DP_INSTALL_PROFILE=standard/https://github.com/shaal/drupalpod

(You should see standard profile installed)

Run ddev composer require drupal/gin
Open the Drupal website, you will see installation screen (even that the website was just installed and configured already)

Expected behavior

Users should be able to run composer commands without interrupting the flow of development.

Screenshots

Version and configuration information (please complete the following information)

• Issue page
• Issue branch
• Drupal core version
• Project type
• Core
• Module
• Theme

Additional context

DrupalPod is using @joachim's core-development project (https://github.com/joachim-n/drupal-core-development-project) for Drupal core issues.
It includes patching of web/index.php, web/update.php and Drush.

Direction to solve the issue -
instead of manually patching the files, add the required patching as part of composer.json, every time composer runs it will repatch the files as expected.