There are cases where `WaitUntilOnPage` will incorrectly render, such as at the beginning if the upper components hasn't expanded to full size, so `WaitUntilOnPage` would be briefly visible.
Added a 300ms debounce to fix this, which would also improve scrolling performance a bit by doing less. Hopefully 300ms is enough for the upper components to inflate to full size.
## Issue:
Fixes 4549 `Mature content + navigating to URLs directly`
_If a user navigates to mature content directly, we currently show the page even if mature content setting is not enabled. With our recent mature content verification setting, we should hide the page until the user turns it on - we can prompt directly on the file page._
## Changes:
1. Show basic info of the claim like URL and Title, so that user knows which page is being blocked.
2. Initially, I had 2 "boxes" -- one for the title and another for the message. It felt a bit messy, so `FileTitle` was augmented to house everything in one box.
## Issue
When navigating back and forth between a File and Channel page, the back-action will be laggy (no response) if the channel contains a lot of comments and is in the midst of resolving them.
## Changes
The "full" fix would be to batch-load comments, as this would improve the performance of fetching both Channel and File comments. For now, this commit focuses on the Back action problem only.
Skip fetching comments by not mounting 'ChannelDiscussion' until the tab is selected. I couldn't find anything in the Reach UI documentation on how to not render inactive `TabPanel`s, so I used the straight-forward state method.
