Add "environment" dropdown to pod logs screen

What does this MR do?

• Adds a environment dropdown to switch between environments
• Adds a form-group look and feel to all dropdowns
  • Responsive layout is taken into account
• Adds polling, to the backend can populate the log data asynchronously
  • Corresponding error handling
• Allows for a "default" pod
  • Assumes the first pod log is loaded

Future improvements

• Consider a large number of envs could be loaded #33017 (closed)

Screenshots

Before

Before	After

Video (recorded on a slow network... ⏲ )

Responsive

mobile	desktop

Error state

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content

Performance and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Related to #5769 (closed)