[ML] [Accessibility] Use non visual language to announce bottom bar on file data viz

[aphelionz]

Steps to reproduce (assumes ChromeVox or similar)

1. Navigate to Machine Learning
2. Tab to Data Visualizer
3. Upload a Valid File
4. Go to File Contents / Analysis Screen

Actual Result

The screenreader announces that 'There is a new menu opening with page-level controls at the bottom of the page'.

Expected Result

Non-visual language should be used in place of "bottom of the page" ... suggest use of "end of document?"

Meta Issue #26855

Kibana Version: 6.5

Relevant WCAG Criteria: 3.2.2 On Input

[elasticmachine]

Pinging @elastic/ml-ui

[peteharverson]

The screen reader text for the bottom bar is set in the EuiBottomBar component. Raised elastic/eui#1696 to get this text altered to use non-visual language.

[peteharverson]

This has been fixed by the change to EuiBottomBar in elastic/eui#1727, with the the screen reader text changed to use non-visual langauge There is a new menu opening with page level controls at the end of the document.