web: codemod `web/user/settings/codeHosts` components to CSS modules

Created by: gitstart-sourcegraph

Description:

This PR results from the global-css-to-css-modules codemod application with some manual fixes, caused by the usage of global CSS classes tied to a React component in other parts of the codebase.

Refs:

• SG Issue
• Gitstart Ticket

Success criteria:

The stylesheets in the following directories are converted to CSS modules.

• client/web/src/user/settings/codeHosts