Add --prettier flag for Prettier-formatted changelogs

[danroc]

This PR adds a new --prettier flag. When enabled, this flag signals that the tool should expect the changelog to be formatted using Prettier. By default, this flag is set to false, ensuring backward compatibility with all existing CHANGELOG.md files.

The primary motivation for this change is to overcome a current limitation of auto-changelog. At present, our tool does not support the changelog format provided by Keep a Changelog (version ^1.1.0).

Fixes: #60

[Mrtenz]

Rather than running Prettier programatically, couldn't we just remove the changelog from the ignore list, and disable formatting with a flag?

https://github.com/MetaMask/metamask-module-template/blob/main/package.json#L45

[danroc]

I'm not sure. The update command would need to be paired with an external formater everytime it's executed. But we could add another flag (--ignore-formatting?) available only for validate.

[Mrtenz]

I'm not sure. The update command would need to be paired with an external formater everytime it's executed. But we could add another flag (--ignore-formatting?) available only for validate.

We run Prettier regardless, hence why it's currently ignored.

[Gudahtt]

Not always at the same time as updating the changelog though.

There's also the validate command; it's sensitive to formatting changes so we'd need to run prettier programmatically during validation to avoid breaking that.

[danroc]

If we ignore formating, enforcing that the sections are always in the same order may be more complex.

Yes @Gudahtt, this is why I passed the formatter to both validate and update commands.

[Mrtenz]

Ok, makes sense!

[danroc]

If we are not willing to add a formatter, I suppose I could workaround like this:

Replace update with:

auto-changelog update && prettier

And replace validate with:

auto-changelog validate --fix && prettier

and then check if the CHANGELOG.md file changed, although it's not very elegant.

[Gudahtt]

LGTM!