[A11y][Screenreader] Add accessible information for the bubbles view

[Dananji]

Description

When using the timeliner with a screen-reader, the screen-reader doesn't provide any information on the bubbles view and it skips that entire region. This bubbles view is built as an SVG in the timeliner view page.

Screen reader/keyboard a11y observation	Impact and/or possible solutions
Screen reader is not aware of the bubbles view ❌	The bubbles in the timeliner is an SVG, and it's quite complicated to make the user interaction with bubbles accessible. However, to start off this can be treated as an image and can be supplemented with a descriptive alt text?
Tab-order entirely skips the bubble view ❌	This could be added to the tab-order and with a descriptive alt text for the bubbles would help screen readers make more sense of the page?

Part of avalonmediasystem/avalon#6435.

Possible solutions to solve the screen-reader accessibility of the bubbles;

• accessible SVGs for the bubbles
• alt-text for the bubbles SVG

Done Looks Like

• Investigate the possibility of using accessible SVGs
• Add bubble view to the tab-order of the page
• Provide the bubbles view as a region on the page so, it is present on the web rotor of the screen-reader