[console] update to latest styleguide

[epixa]

The code in Console does not match our styleguide in most places since it was copied over from a different project entirely. We should update that entire plugin to reflect the coding styles and conventions of the rest of the project so that future contributions to it can be evaluated just like we would any other.

• Update console root code so it passes the global linter console: clean up styles for entry and server code #9646
• Update code in server directory to pass the global linter console: clean up styles for entry and server code #9646
• Update code in public directory to pass the global linter
• Update code in api_server directory to pass the global linter
• Manual pass on code to update it to more modern styles (e.g. class syntax)

[elasticmachine]

Pinging @elastic/es-ui

[epixa]

I'm going to close this as I don't think we're going to bulk update the code style just for the sake of it, and a pretty large refactor of console is going to happen anyway.