Speed up auth

[htdvisser]

Summary

This pull contains some optimizations for the authentication and authorization flows of the Identity Server.

Refs #1666 and #1393

Changes

• Lower the number of PBKDF2 iterations for API keys and Access Tokens. These secrets are already pretty long at 50 characters, so we don't also need to spend 100ms hashing them.
• Speed up GetUser (which is called on every request) by eliminating an extra query for the Account model.
  • Same for Organization, as this is basically the same code.

Testing

Covered by existing tests

Notes for Reviewers

There's still much more work to do, but these changes already give enough improvement to make it worth the PR.

Checklist

• Scope: The referenced issue is addressed, there are no unrelated changes.
• Compatibility: The changes are backwards compatible with existing API, storage, configuration and CLI, according to the compatibility commitments in README.md for the chosen target branch.
• Documentation: Relevant documentation is added or updated.
• Changelog: Significant features, behavior changes, deprecations and fixes are added to CHANGELOG.md.
• Commits: Commit messages follow guidelines in CONTRIBUTING.md, there are no fixup commits left.

[kschiffer]

LGTM