[TASK-977] Switch account sidenav to style module

[jamesrkiger]

Checklist

1. If you've added code that should be tested, add tests
2. If you've changed APIs, update (or create!) the documentation
3. Ensure the tests pass
4. Run ./python-format.sh to make sure that your code lints and that you've followed our coding style
5. Write a title and, if necessary, a description of your work suitable for publishing in our release notes
6. Mention any related issues in this repository (as #ISSUE) and in other repositories (as kobotoolbox/other#ISSUE)
7. Open an issue in the docs if there are UI/UX changes
8. Create a testing plan for the reviewer and add it to the Testing section

Description

We will be updating the account sidenav for the organizations project and I am taking the opportunity to remove bem components here.

Testing

Compare account sidenav in this PR to its appearance on main. This PR shouldn't be making any visual changes.

[notion-workspace]

Account Routing and Sidenav

[duvld]

Somehow the icons and spacing are 1 or 2 pixels larger. Barely noticeable and I can't find where it's happening. I think it's fine though, no breaking changes.

[notion-workspace]

Account Routing and Sidenav

[jamesrkiger]

Somehow the icons and spacing are 1 or 2 pixels larger. Barely noticeable and I can't find where it's happening. I think it's fine though, no breaking changes.

Good catch. It was from a css rule I hadn't copied into the style module. Fixed now.