feat: transaction manager

[wangsijie]

Summary

Sign in process is a transaction: generate random stuff, go to logto website, then redirect back to user's site and verify the stuff created.

Those random stuff is per-transaction, can not be reused, so need a manager to save transaction data.

Linear Issue Reference

Testing

UT

[gao-sun]

I would prefer to use session for naming consistency instead of transaction.

[wangsijie]

I would prefer to use session for naming consistency instead of transaction.

agree, session would be more familiar in auth

[simeng-li]

All comments addressed

@simeng-li approved on behalf