Update deps, general cleanup, improve roles UI, add role visibility.

[jnms-me]

Fixes #388

TODO:

• Add one final migration to convert roles.client_id into visibility:
  • NULL => global
  • NOT NULL => limited, add (role_id, client_id) to roles_limited_to_clients
• Use replace usages of role.client_id with visibility.

dfcacaa tools(guix): Add manifest.scm.
58cf5cb deps: Pin rust toolchain version.
775ae6f deps: Run cargo update.
266d348 deps: Run cargo upgrade.
cbccd14 deps(cargo): Update askama to 0.15.6.
313b008 deps(cargo): Complete the migration to askama 0.15.
8cbcfa7 lint: Fix rustc warnings.
ffbb39c style: Run cargo fmt.
b1aba1a feat: Add client column to the roles overview page.
579596b lint: Use $crate in macros.
a70e21a style: Organize imports.
9e11fee build: Make package.json a private module.
74b3a33 style(templates): Use uniform spacing for inline rust code.
d859777 style(editorconfig): Set html tab width to 2.
f32f356 style(editorconfig): Set charset and whitespace control flags.
f8caa77 lint(templates): Reformat and clean up html templates.
3cd3b17 refactor(templates): Replace match with if-let for Result types.
6320611 fix(ui): Correct typos in role page.
5c7e849 style(templates/roles): Use multilines for long input tags.
4402769 feat(frontend): Add editable description to the show_role page.
92c9fca fix: Set content-type to html for error pages.
dab468a tools(hooks): Remove preamble intended for pre-push from pre-commit.
416f704 feat(backend): Implement role_controller::update_description route.
55fa45a tools(hooks): Add optional cargo sort-derives to pre-commit hook.
5d54687 style: Sort derives.
3ea25ed style: Use consistent order for route function args and add comments indicating source of the args.
f546b59 style: Order routes in lib.rs in their function declaration order.
b5745cb chore(gitignore): Add .diesel_lock.
9530567 fix(migrations): Fix diesel schema.rs auto-generation, update docs.
5397bf3 db: Rename users_roles to users_assigned_roles and clients_roles to clients_assigned_roles.
723b492 db: Add visibility field to roles;
368365b db: Add roles_limited_to_clients table.
ba8f62b feat(frontend): Add editable visibility to the show_role page.
5a9cba8 feat(frontend): Use drop-downs for client/user selection on the show_role page.
2f52d81 feat(backend): Implement role_controller::update_visibility route.
794927d style: Move roles_controller::delete_role to bottom of source file.
3ffcc15 feat(frontend): Improve error/success messages returned by roles_controller.
6bacccd feat(backend): Implement roles_controller::add_limited_to_client route.
a28afee feat(backend): Implement roles_controller::delete_limited_to_client route.
5ef391d feat(frontend): List “limited to” clients on show_role page.
4946234 refactor(frontend): Use for-else for placeholders on show_role page.
de08d6c db: Fix down.sql of some old migrations.
3336a94 db: Remove client_id from roles, migrating data to visibility and roles_limited_to_clients.
a79163d tests: Fix tests.
5c97e8f feat(backend): Implement /.well-known/openid-configuration route.
c557183 dev(test_client): Improve python test_client.