[SG-37914] Extract bootstrap style import `buttons`

Created by: gitstart-sourcegraph

Description

Extract / Remove usage of bootstrap's style sheet import on codebase.

Success criteria

• Bootstrap button import is removed from client/branded/src/global-styles/index.scss
• Migrate remaining usage of btn, btn-* classes to wildcard component.

Implementation Detail

• Migrate .btn-icon usage to <Button variant="icon">
• Migrate .btn-link usage to <ButtonLink />, if it's not a good fit, migrate to <Button variant="link" />
• Migrate .btn-block usage to <Button display="block" />
• Migrate remaining usage of <button ...> on codebase to wildcard <Button /> component.
• Remove usage of @import 'bootstrap/scss/buttons'
• Verify there are no UI diff as a result of any of the steps above.

Refs

Gitstart ticket SG Issue

Test Plan

• Identify migrated usage of bootstrap class.
• Verify that they have no UI diff as a result of migrations carried out in this PR.
  • To test client/web/src/org/members/AddMemberToOrgModal.tsx and client/web/src/org/members/InviteMemberModal.tsx
    • open client/web/src/org/area/routes.tsx and comment out Line 25 - the condition for settings/members
    • go to /organizations/sourcegraph/settings/members on the web app.

Links

• UserCodeHosts.tsx
• TourTask.tsx in storybook
• HomeTab.tsx

App preview:

• Web
• Storybook

Check out the client app preview documentation to learn more.