19.3-RC16

Changes compared to: 19.3-RC15

Non user facing:

• Makes the Word complexity assessment upsell not show in all content types for unsupported languages. #18680
• Fixes a bug where the link to the insights section inside of the "Flesch reading ease has moved" notification inside of the sidebar would not link to the insights modal in the sidebar, but to the insights section in the metabox instead. #18679
• Splits up the shortlinks used in the "Flesch reading ease has moved" notification to one used in the metabox and one used in the sidebar. also #18679
• Changes the copy of the "Flesch reading ease has moved" notification when insights are disabled. also #18679