Use oauth2-client instead of sk-auth (WIP)

example.env

package-lock.json

package.json

src/app.d.ts

src/hooks.server.ts

src/lib/server/auditors/config.ts

src/lib/server/auditors/queries.ts

src/lib/server/config.ts

src/lib/server/oauth2.ts

src/lib/server/openid_connect_handler.ts

src/lib/server/user_handler.ts

src/routes/auth/login/+server.ts

src/routes/auth/login_callback/+server.ts

src/routes/auth/logout/+server.ts

src/routes/auth/logout_callback/+server.ts

src/routes/auth/metadata/+server.ts

src/routes/authentication/[...auth]/+server.ts