Issue-39: Allow post display options to be edited without a post being selected

[mogmarsh]

Pull Request Title

Allow post display options to be edited without a post being selected (#39)

Description

This pull request addresses the issue "Allow post display options to be edited without a post being selected" (#39). The changes made in this PR will make the items under the Post section of the sidebar visible even if a post is not selected in the Newsletter Single Post block. Additionally, the checkboxes will now be draggable, enabling users to set the "order" attribute.

Issue Number

Closes #39

Related Issue URL

#39

Notes

• Please test the changes made in this PR to ensure they work as expected.
• Ensure that the post display options can be edited without a post being selected.
• Verify that the draggable checkboxes for setting the "order" attribute work and are only enabled on the Template post type.
• Review the code changes made in this PR to guarantee they follow best practices.

[attackant]

No blockers, but ideas for you 🐙

[attackant]

I went back and forth on this but something like this may be cleaner, but really not sure:

const displayPreferences = {
     'image': showImage,
     'byline': showByline,
     'excerpt': showExcerpt,
     'content': showContent,
     'cta': showCta,
     'title': true
  };

  const isShown = (item: string) => displayPreferences[item] ?? false;
  
  const toggleShown = (item: string) => {
    setAttributes((prevAttributes: EditProps["attributes"]) => ({
      ...prevAttributes,
      [`show${item.charAt(0).toUpperCase() + item.slice(1)}`]: !prevAttributes[`show${item.charAt(0).toUpperCase() + item.slice(1)}`]
    }));
  };

[mogmarsh]

I like this suggestion, but this work should be temporary (see #48) so I'm going to leave it as is for now.

[attackant]

Also for the ternary's in this file we may consider logical nullish
let postTitle = record?.title.rendered ?? '';
in place of
let postTitle = record ? record.title.rendered : '';