Extend conflict resolver to handle all pages-graphql files(on promote)

[vitorflg]

What is the purpose of this pull request?

• It adds an extension of the conflict resolver, resolving conflicts for all pages-graphql files pending a rebase. I'm using the MineWinsConflictResolver of the @vtex/api package.

What problem is this solving?

Slack thread

How should this be manually tested?

• You can test it yarn linking all dependencies(@vtex/api, this module, and the toolbelt), and running with the alias:
  vtex-test promote After that, listing to conflicts should return an empty array.

Concerns

• The body of the content comes in the getConflicts request. It should have a maximum of 100 MB added to memory. I don't think it's an issue, but it's something I thought about as a possible side-effect.

Screenshots or example usage

Types of changes

• Refactor (non-breaking change that only makes the code better)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Requires change to documentation, which has been updated accordingly.

Chores checklist

• Update CHANGELOG.md

[victorhmp]

Code LGTM, but check the CI errors ;)

[filafb]

LGTM