Implement pre-pub state for the rule

[jehlers]

There are 5 main parts:

• [x] Homepage message
• [x] Hiding the XX FR XXXX citation in the global header
• [x] Updating the preamble introduction where we won't have information about the comment period
• [x] Disabling the comment links in the sidebar like when the comment period is closed
• [x] Showing a message/alert if the write mode tab is clicked (similar to the when the comment period is closed)

Here's a design for the homepage during the pre-pub phase:

For the other parts of the tool that need to mention that the rule isn't yet published:

• Preamble introduction that mentions the dates of the comment period:
  • Can we hide the X days countdown?
  • Change the comment period date to say "The comment period is not open."
  • Change the published date to say "The rule is not yet published in the Federal Register."

• Let's follow the pattern we have for when the comment period is closed if someone clicks on the write mode tab:

[cmc333333]

@tadhg-ohiggins is handling the home page part

[cmc333333]

All merged