[ML] Trained Models: Model being downloaded is not announced at all

[bhavyarm]

Description
When user clicks on download model, the Kibana UI displays the information about the download but this doesn't have any focus on it and doesn't get announced at all

Preconditions
Machine Learning -> Model management ->Trained models page

Steps to reproduce

1. Navigate to Machine Learning -> model management ->trained models page
2. Run voiceover
3. Click on "Download " on one of the models
4. Kibana displays the download information but this doesn't get announced.
5. Neither does this download information has any keyboard focus on it (perhaps not important_

Kibana Version: 8.18.0

OS: OS X

Browser: Chrome latest

WCAG or Vendor Guidance (optional)

• Understanding SC 4.1.2: Name, Role, Value (Level A)(https://www.w3.org/WAI/WCAG22/Understanding/name-role-value.html)
• Understanding SC 2.1.1: Keyboard (Level A)(https://www.w3.org/WAI/WCAG22/Understanding/keyboard.html)

Related to: https://github.com/elastic/kibana-team/issues/1559

[elasticmachine]

Pinging @elastic/ml-ui (:ml)

[elasticmachine]

Pinging @elastic/kibana-accessibility (Project:Accessibility)