ci(*:skip) Update e2e tests directory structure

[danielnugraha]

Issue

Description

Related issues/PRs

Proposal

Explanation

Checklist

• Implement proposed change
• Write tests
• Update documentation
• Make CI checks pass
• Ping maintainers on Slack (channel #contributions)

Any other comments?

[panh99]

Since we plan to make each E2E test a complete Flower App, could you:

1. Rename the module name from, e.g., baree2e to e2e (or bare_e2e if you want)
2. Change the subdir fields to e2e in .github/workflows/e2e.yml accordingly
3. Update the [tool.flwr.app.components] section in all TOML files accordingly, e.g., changing baree2e.server_app:app to e2e.server_app:app.
4. Update name fields in [project] section in all TOML files to give each E2E test a unique name, instead of just e2e_test, e.g., bare-e2e-test. (Btw, the app name cannot contain _, and thus please use - for app names instead.)