[APM] New platform migration: Lift up ui/chrome dependency

[jasonrhodes]

Broken-out from #32894

Remove static webpack-magic imports for ui/chrome and replace with a single import in our top-level index file.

AC:

• import x from 'ui/chrome' should only appear once in APM, in the top-level file
• all other uses of ui/chrome should be provided from inside our app, either by DI, context, or some other singleton approach

Known uses of ui/chrome:

• chrome.addBasePath() in several places
• chrome.breadcrumbs.set()
• chrome.getInjected('apmIndexPatternTitle') in quite a few places
• chrome.getUiSettingsClient() used for 'dateFormat:tz' in WatcherFlyout
• chrome.navLinkExists('apm') in toggle_app_link_in_nav
• used in our apm/public/index file:
  • chrome.helpExtension.set()
  • chrome.setRootTemplate(template)
  • chrome.disableAutoAngularUrlEncodingFix()

[elasticmachine]

Pinging @elastic/apm-ui

[sorenlouv]

@jasonrhodes I'm starting to look into this. I'll create the shims for the new platform, and lift up ui/chrome.

[sorenlouv]

This depends on #34533