Update UI flow to open Kyma Companion

[chriskari]

Description
The Kyma Companion UI flow needs to be updated to align with the latest UI/UX design specifications. The updated design requires the Companion to be opened via an AI icon in the header bar. Upon opening, users should see:

1. An introductory message.
2. Initial question suggestions fetched from the POST /conversation endpoint.

This approach differs from the previous POC implementation, where:

1. The assistant could be opened via buttons on individual resource pages.
2. Suggestions were displayed in a popover, and the chat interface was opened only after a user selected a suggestion or submitted a custom prompt

Tasks:

• refactor the previous flow as well as the CompanionOpener component to match the updated design

The necessary adjustments include, but may not be limited to

• Upon clicking the AI icon fetch prompt suggestions and open the chat interface
• Populate the chat with an introductory message as well as the fetched suggestions
• Remove the CompanionOpener component along with unneeded functionality