feat(high contrast): add border to some hover states

[srambach]

Fixes #87

Adds a high contrast border on a pseudoelement for filter side panel and vertical tabs when hovered.

Will need PatternFly 6.4 for the high contrast tokens.
Since there is no theme switcher, add pf-v6-theme-high-contrast to the html tag to trigger high contrast mode.

[srambach]

The build for this is failing, and cursor says

"The error indicates that your project is configured to use Yarn 4.5.3 (as specified in the packageManager field), but the CI environment is using Yarn 1.22.22. The solution is to enable Corepack, which manages package manager versions automatically."

and recommends adding

name: Enable Corepack
run: corepack enable

before running yarn install --frozen-lockfile
Can someone advise? @nicole, @wise-king-sullyman ?

[thatblindgeye]

This should be good to rebase after a PR for workflows was merged in. Just a note below.

[thatblindgeye]

Nicole had suggested I try keeping the patternfly versions in extensions as what they were, and just updating the docs framework version to the latest (6.28.9). We could try that here so that at least the docs build will allow showing the high contrast styles.

We would also probably want to add to the patternfly-docs.config.js file the following to get the switchers showing up and make it easier to test HC styles:

  hasThemeSwitcher: true,
  hasHighContrastSwitcher: true

[patternfly-build]

Preview: https://catalog-view-pr-catalog-view-91.surge.sh

A11y report: https://catalog-view-pr-catalog-view-91-a11y.surge.sh

[lboehling]

The vertical tabs look good in high contrast, but i'm seeing some additional hover states being applied to the filters in this PR. I don't think we need the bkg color/high contrast border on the filter checkbox items. otherwise this looks good!

[srambach]

@lboehling @thatblindgeye I didn't add the hover background, just the outline. Git blame points to a change by @nicolethoen - anyone know why this was added?

[thatblindgeye]

There is this issue that might handle this: #88

[srambach]

So it looks like maybe it was applied to the filter side panel by accident and was only meant to be the vertical tabs?
#73 comments talk about a hover background on vertical tabs but it was also applied to the filter side panel, perhaps erroneously?