Kibana page layout shared components

[myasonik]

Thinking about improving page layout for Kibana with coming improvements from EUI (to help align Kibana and Solutions) there are several a11y issues around it that could be eliminated through a stricter layout service or series of components.

For a generic page setup:

• Could guarantee main and h1
  • Would be helpful to have a consistent place to jump to (https://github.com/elastic/kibana/issues/38980) and would solve focus order (number 3 in https://github.com/elastic/kibana/issues/42379)
  • We struggle with consistent landmarks (e.g., number 13 https://github.com/elastic/kibana/issues/71666)
  • We keep playing whackamole with h1 issues (https://github.com/elastic/kibana/issues/61870, https://github.com/elastic/kibana/issues/44544, )

For our common "search box + table" page:

• Would close repeat issues like missing table captions (https://github.com/elastic/kibana/issues/51070, https://github.com/elastic/kibana/issues/44542, https://github.com/elastic/kibana/issues/42400), and no search results being announced (https://github.com/elastic/kibana/issues/62477)
• Could allow for quickly rolling out enhancements (https://github.com/elastic/kibana/issues/28143)

For tab pages:

• Stop allowing links in buttons or vice versa (https://github.com/elastic/kibana/issues/77828, https://github.com/elastic/kibana/issues/29344)

For left hand sub nav:

• Could enhance nav UI {issue missing}

[ryankeairns]

Another think we'll attempt to provide here are top and bottom banners as described in #17298

[elasticmachine]

Pinging @elastic/kibana-design (Team:Kibana-Design)

[cchaos]

@elastic/shared-ux I'd like to evaluate the outstanding items on the list to see if they're still valid and/or close this issue.