Article editor improvements

[jonkafton]

What are the relevant tickets?

• https://github.com/mitodl/hq/issues/9558

Description (What does it do?)

Series of bug fixes and improvements:

Update banner title/subtitle placeholders

To test:

• Open http://open.odl.local:8062/articles/new
• The placeholders should read "Add a title" and "Add a subheading".

---

Move the “Add image” button to the insert dropdown.

To test:

• Open http://open.odl.local:8062/articles/new
• Confirm that the insert image action is now in the "Insert" menu.

---

BUG: Draft article publish button not enabled

To test:

• Open http://open.odl.local:8062/articles/new
• Add a title and save as draft.
• Hit the edit button.
• Confirm the the publish button is enabled and clickable.

---

Improve visibility of image sizing controls

To test:

• Open http://open.odl.local:8062/articles/new
• Insert an image.
• Confirm that the image controls are clearly visible

---

Reduce the width of the "wide" image option

To test:

• Open http://open.odl.local:8062/articles/new
• Insert an image.
• Set the image to wide (middle button).
• Set a title and save the article.
• Confirm that the image has a max width of 1400px.

---

BUG: Alert on save error is missing

To test:

• Open http://open.odl.local:8062/articles/1/edit
• Stop the web service or block the save request in dev tools (PATCH http://api.open.odl.local:8065/api/v1/articles/1/)
• Hit "Save as Draft".
• Confirm that you see an error alert.

---

Article detail load spinner is not vertically centered

To test:

• Open http://open.odl.local:8062/articles/1
• Confirm that the load spinner is centered in screen.

---

BUG: Byline does not show author

To test:

• Save or publish an article.
• Ideally logged in with a different user, confirm that the author name is displayed.

---

Read time is missing

To test:

• Open http://open.odl.local:8062/articles/new
• Grab some lorem ipsum and paste in.
• Confirm that the read time in the byline bar updates as you add text. It's set to 250 words per minute, rounded to nearest minute and does not display anything if minutes round to zero.
• Save the article.
• Confirm that the read time is displayed.