(Accessibility) Missing Skip Navigation to skip directly to the main page content for Kibana/Uptime page

[barlowm]

Steps to reproduce (assumes ChromeVox or similar)

1. Open Uptime Home Page
2. Press TAB key
3. ChromeVox reads "Goto Home Page, Link"
4. Subsequent pressing of the TAB key will navigate the user through all the menu and list options eventually taking the user to the "Goto Uptime Homepage, internal link"

There is no "Bypass Block" mechanism to skip directly to the Uptime page Content

Expected Result
There should be an accessible link at the start of the page to allow a user to skip around all the normal page navigation elements to get directly to the main content of the page.

Meta Issue
Kibana Home
Improve Kibana Accessibility

Kibana Version:
7.0

Relevant WCAG Criteria:
2.4.1 Bypass Blocks: A mechanism is available to bypass blocks of content that are repeated on multiple Web pages. (Level A)

[barlowm]

WebAIM has an excellent article on how to code [Skip Navigation links}(https://webaim.org/techniques/skipnav/)

[elasticmachine]

Pinging @elastic/uptime

[andrewvc]

This is a global Kibana accessibility issue so beyond our scope.