[Odie] Wapuu scroll rework

[AllTerrainDeveloper]

This is a rework on how the scrolling is working in Wapuu client, as well as a better handling for extra contact flows.

#93109
#93108

Proposed Changes

The changes are still using React References, but this time only for the parent element. This way we can safely and easily iterate on children looking for tags (is last element, is last user message, is error message, is feedback message, etc). That way we improve greatly the control over the scrolling.

Main changes

1. Styling changes, added min heights to extra contact flows, that were adding UI shifts
2. Added a loader while the UI is not stable
3. Removed the feeling stuck link when we are already presenting a different contact flow
4. Added corrections and debounces in order to keep scroll working while changing UI elements
5. Removed extra contact options for messages where user was requesting to contact user support, and clicked on thumbs down (that was adding an extra element to contact in addition with the regular one)

Why are these changes being made?

We needed urgently to update the user experience with the scrolling

Testing Instructions

Check scroll behavior

1. Start a new conversation and send several messages. When available space and Wapuu's long response, your last message (as user) will stay at the top
2. Adding new message will show the loader in the bottom
3. Disliking a message will keep the new message in the bottom without flickering
4. If you click on "Jump to recent" the beginning of the last message will remain at the top of the container, allowing you to scroll a bit more to keep reading

Check contact flows

1. Check double contact flow options
2. Start a new conversation
3. Ask for human support in your first message
4. Click on Thumbs down icon
5. Assert that only one button to contact WordPress is presented even after closing and reopening the chat.

[matticbot]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-115473

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-115473&env=jetpack

Automattic for Agencies live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-115473&env=a8c-for-agencies

[matticbot]

Here is how your PR affects size of JS and CSS bundles shipped to the user's browser:

Async-loaded Components (~707 bytes removed 📉 [gzipped])

name                               parsed_size           gzip_size
async-load-automattic-help-center      -1999 B  (-0.4%)     -707 B  (-0.4%)

React components that are loaded lazily, when a certain part of UI is displayed for the first time.

Legend

What is parsed and gzip size?

Parsed Size: Uncompressed size of the JS and CSS files. This much code needs to be parsed and stored in memory.
Gzip Size: Compressed size of the JS and CSS files. This much data needs to be downloaded over network.

Generated by performance advisor bot at iscalypsofastyet.com.

[matticbot]

This PR modifies the release build for the following Calypso Apps:

For info about this notification, see here: PCYsg-OT6-p2

• help-center
• notifications
• wpcom-block-editor

To test WordPress.com changes, run install-plugin.sh $pluginSlug wapuu/improve-code-and-refactor on your sandbox.