Extract bootstrap style import `@import 'bootstrap/scss/card'` in `client/vscode`

Created by: gitstart-sourcegraph

Problem statement

We depend on Bootstrap styles in our global styles a lot. But we don't plan to move forward with Bootstrap because we're working on our design system called Wildcard. To ease the transition to our styles and gain more control over visual changes, we want to move Bootstrap styles that we need into our codebase and eventually drop Bootstrap dependency.

Ref

https://github.com/sourcegraph/sourcegraph/issues/39345

Success criteria

1. All use cases of card-* are migrated to use wildcard's Card component.

Implementation details

1. Remove bootstrap import @import 'bootstrap/scss/card' in forkedBranded.scss.
2. Covert use cases of card-* className to Card wildcard component.
3. If step 2. above is not doable, let's copy style rule from bootstrap to be used internally.

Time estimate

• Pull requests with frontend lines changed should take 2 hours at maximum. Ping the reviewer in the spec pull request if time-consuming changes are required.
• Split the work into multiple pull requests if the total diff is bigger than 450 lines of code.