Ensure panels opened via toolbar buttons get closed when clicked again (shields, vpn, wallet)

[petemill]

Resolves brave/brave-browser#22026

Submitter Checklist:

• I confirm that no security/privacy review is needed, or that I have requested one
• There is a ticket for my issue
• Used Github auto-closing keywords in the PR description above
• Wrote a good PR/commit description
• Squashed any review feedback or "fixup" commits before merge, so that history is a record of what happened in the repo, not your PR
• Added appropriate labels (QA/Yes or QA/No; release-notes/include or release-notes/exclude; OS/...) to the associated issue
• Checked the PR locally: npm run test -- brave_browser_tests, npm run test -- brave_unit_tests, npm run lint, npm run gn_check, npm run tslint
• Ran git rebase master (if needed)

Reviewer Checklist:

• A security review is not needed, or a link to one is included in the PR description
• New files have MPL-2.0 license header
• Adequate test coverage exists to prevent regressions
• Major classes, functions and non-trivial code blocks are well-commented
• Changes in component dependencies are properly reflected in gn
• Code follows the style guide
• Test plan is specified in PR before merging

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on
• All relevant documentation has been updated, for instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-Compatibility-Exceptions-in-Brave
  • https://github.com/brave/brave-browser/wiki/QA-Guide
  • https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

[nullhook]

lgtm

[stephendonner]

Verified PASSED using

Brave | 1.39.73 Chromium: 101.0.4951.34 (Official Build) nightly (x86_64)
-- | --
Revision | 8f93af5d759634c5256b65997dedd138ed60992f-refs/branch-heads/4951@{#710}
OS | macOS Version 11.6.5 (Build 20G527)

Steps:

1. installed 1.39.73
2. launched Brave
3. enabled Experimental VPN... via brave://flags
4. clicked Relaunch to restart Brave
5. clicked on the icons

In all cases, tested:

• clicking the icon invokes a doorhanger panel, which remains until further, specific click(s)
• clicking inside the panel does NOT dismiss (expected)
• clicking again on the icon dismisses the doorhanger panel
• clicking anywhere outside of the doorhanger panel dismisses it
• panel is dismissed upon pressing esc
• context-clicking Wallet and VPN icons shows a Hide [button in toolbar] descriptive text (filed Descriptive text for Wallet and VPN icons on toolbar need to be consistent brave-browser#22436)