Polish blueprint mode of pre-chat starter prompts

[compulim]

Changelog Entry

Added

• Added blueprint of starter prompts in the Fluent theme, in PR #5270, #5276 and #5279, by @OEvgeny and @compulim

Description

This is continuation of #5276.

Polishes the blueprint of starter prompts and supports RTL in animation.

Specific Changes

• Corrected gaps between skeleton of title and subtitle
• Updated animation to support RTL
• Also fixed flakiness test related to upload
  • After upload and send, should wait for outgoing activities to be sent

• [x] I have added tests and executed them locally
• [x] I have updated CHANGELOG.md
• [x] ~I have updated documentation~

Review Checklist

This section is for contributors to review your work.

• [x] ~Accessibility reviewed (tab order, content readability, alt text, color contrast)~
• [x] ~Browser and platform compatibilities reviewed~
• [x] CSS styles reviewed (minimal rules, no z-index)
• [x] ~Documents reviewed (docs, samples, live demo)~
• [x] ~Internationalization reviewed (strings, unit formatting)~
• [x] ~package.json and package-lock.json reviewed~
• [x] ~Security reviewed (no data URIs, check for nonce leak)~
• [x] Tests reviewed (coverage, legitimacy)