Simplify admin console and remove superfluous icons

[agh1]

Overview

This slices off three commits from #17259 for ease of review. #17279 will need to be merged first, as that removes most uses of the check.gif file that this removes.

This completely replaces the Administration Console with one that's much simpler. The dozens of icons are gone, and you don't need to click the little triangles to get through to where the descriptions are. The page is responsive, displaying a single column on narrow screens.

Also, the old console hard-coded which components got sections, while this works from the list of enabled components.

Before

When you first open the page:

When you click a little triangle to expand a section:

After

[civibot]

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[jaapjansma]

• General standards
  • Explain (r-explain)
    • PASS : The goal/problem/solution have been adequately explained in the PR.
  • User impact (r-user)
    • PASS: The change would be intuitive.
  • Documentation (r-doc)
    • PASS: The changes do not require documentation.
  • Run it (r-run)
    • PASS: We checked in the test environment of this PR and compared it to dmaster. We also asked for feedback from our CiviCooP collueges and we didn't got much feedback. So this PR is good for us.
• Developer standards
  • Technical impact (r-tech)
    • PASS: The change preserves compatibility with existing callers/code/downstream.
  • Code quality (r-code)
    • PASS: The functionality, purpose, and style of the code seems clear+sensible.
  • Maintainability (r-maint)
    • PASS: The change sufficiently improves test coverage, or the change is trivial enough that it does not require tests.
  • Test results (r-test)
    • PASS: The test results are all-clear.

@eileenmcnaughton or @mattwire could one of you merge this PR?