internal/sessions: session state is domain scoped
internal/sessions: infer csrf cookie, route scoped
proxy & authenticate: use shared cookie name
proxy & authenticate: prevent resaving unchanged session
proxy & authenticate: redirect instead of error for no session on login
internal/config: merge cookies
proxy: remove favicon specific route
proxy: use mock server for tests
proxy: add tests for failures
* Improve test coverage.
* Remove unused http status code argument from SignInPageMethod.
* Removed log package in internal packages.
* Add test to check https scheme is used for authorization url.
* Add unit tests for global logging package.