perf(b-link): convert functional component to regular component (closes #3634)

[tmorehouse]

Describe the PR

Convert b-link to a regular component from a functional component.

When users have a large number of components, which are derived from b-link (b-dropdown-item, b-button, etc), re-rendering can take performance hits due to the re-computation of the event handlers on each render.

Closes #3634

To do:

• updated tests

PR checklist

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

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

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)
• 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 #3637 into dev will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##              dev    #3637      +/-   ##
==========================================
- Coverage   99.26%   99.26%   -0.01%     
==========================================
  Files         224      224              
  Lines        4333     4326       -7     
  Branches     1234     1231       -3     
==========================================
- Hits         4301     4294       -7     
  Misses         26       26              
  Partials        6        6

Impacted Files	Coverage Δ
src/utils/router.js	100% <100%> (ø)	⬆️
src/components/link/link.js	100% <100%> (ø)	⬆️

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