fix(b-dropdown): focus-in handling for Safari and Firefox on macOS/iOS (closes #4328)

[jacobmllr95]

Describe the PR

This PR fixes the focus-in handling for Safari and Firefox on macOS/iOS.

Closes #4328.

PR checklist

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Enhancement
• ARIA accessibility
• Documentation update
• Other (please describe)

Does this PR introduce a breaking change? (check one)

• No
• Yes (please describe)

The PR fulfills these requirements:

• It's submitted to the dev branch, not the master branch
• When resolving a specific issue, it's referenced in the PR's title (i.e. [...] (fixes #xxx[,#xxx]), where "xxx" is the issue number)
• It should address only one issue or feature. If adding multiple features or fixing a bug and adding a new feature, break them into separate PRs if at all possible.
• The title should follow the Conventional Commits naming convention (i.e. fix(alert): not alerting during SSR render, docs(badge): update pill examples, fix typos, chore: fix typo in README, etc). This is very important, as the CHANGELOG is generated from these messages.

If new features/enhancement/fixes are added or changed:

• Includes documentation updates (including updating the component's package.json for slot and event changes)
• Includes any needed TypeScript declaration file updates
• New/updated tests are included and passing (if required)
• Existing test suites are passing
• The changes have not impacted the functionality of other components or directives
• ARIA Accessibility has been taken into consideration (Does it affect screen reader users or keyboard only users? Clickable items should be in the tab index, etc.)

If adding a new feature, or changing the functionality of an existing feature, the PR's
description above includes:

• A convincing reason for adding this feature (to avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it)

[codecov]

Codecov Report

Merging #4426 into dev will increase coverage by 0.05%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##              dev    #4426      +/-   ##
==========================================
+ Coverage   99.86%   99.92%   +0.05%     
==========================================
  Files         251      253       +2     
  Lines        5230     5263      +33     
  Branches     1384     1397      +13     
==========================================
+ Hits         5223     5259      +36     
+ Misses          6        3       -3     
  Partials        1        1

Impacted Files	Coverage Δ
src/components/dropdown/dropdown.js	100% <ø> (ø)	⬆️
src/icons/icon.js	100% <ø> (ø)	⬆️
src/components/dropdown/dropdown-item.js	100% <ø> (ø)	⬆️
src/index.js	100% <ø> (ø)	⬆️
src/components/nav/nav-item-dropdown.js	100% <ø> (ø)	⬆️
src/icons/plugin.js	100% <ø> (ø)	⬆️
src/directives/toggle/toggle.js	100% <ø> (ø)	⬆️
src/components/link/link.js	100% <ø> (ø)	⬆️
src/icons/icons.js	100% <ø> (ø)	⬆️
tests/utils.js	100% <ø> (ø)	⬆️
... and 22 more

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