Add script and documentation for minimizing patches

[code-asher]

We can see the differences between code-server and VS Code with something like this (will have to be tweaked to work in all cases):

#!/usr/bin/env bash
set -euo pipefail

main() {
  cd "$(dirname "$0")/../.."

  local upstream=$1 ; shift
  local main=$1 ; shift

  git diff "$upstream" "$main" --name-only \
    | grep -v 'yarn.lock$' \
    | grep -v '^src/typings/' \
    | xargs git diff "$upstream" "$main" --
}

main "$@"

Example usage:

./diff.bash vscode/release/1.57 origin/main:lib/vscode

So I'm thinking we should make this part of the upgrade process to ensure we don't have differences we shouldn't (currently we do, probably somehow happened in the various squashes) and to help us keep tabs on what we've actually changed. There are changes we've made here that we can move out or refactor to minimize future conflicts.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no activity occurs in the next 5 days.

[jsjoeio]

Not stale