Adds locals when rendering ActionText attachments - #58511

Motivation / Background

ActionText attachments may need additional context from where they're rendered. Right now, there is no way to reference the context which the ActionText::Content is rendered in so it can't really be dynamic.

I ran into this initially rendering ActionText::Content in an admin area where I wanted attachments to render different URLs than the customer facing version.

Another case was rendering some ActionText::Content inside and outside Turbo Frames. When inside, I need to ensure the links in ActionText are rendered with data-turbo-frame="_top" and I really need the context to be passed in.

Detail

Allows users to render ActionText::Content with locals passed along to attachments.

<%= render post.body, locals: {turbo_frame: :_top} %>

These locals are passed along to attachment partials.

@jorgemanrubia would you find this helpful?

Additional Information

I also added a default local in_editor: true for to_editor_html like in_gallery: true for images.

It's common practice to use the same partial for both the regular and editor HTML. You could use this to make links disabled in the editor (a user accidentally clicking a link in the editor could lose their writing) for example:

<%= link_to_if !local_assigns[:in_editor], post.title, post %>

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one change. Unrelated changes should be opened in separate PRs.
• Commit message has a detailed description of what changed and why. If this PR fixes a related issue include it in the commit message. Ex: [Fix #issue-number]
• Tests are added or updated if you fix a bug or add a feature.
• CHANGELOG files are updated for the changed libraries if there is a behavior change or additional feature. Minor bug fixes and documentation changes should not be included.