Fixes 30636
I am adding a handful of additional unit tests but this is ready for
review now. Integrates changes from Victor's PoC for Account Driven User
Enrollment including a nice end to end integration test including the
SAML portion
# Checklist for submitter
If some of the following don't apply, delete the relevant line.
<!-- Note that API documentation changes are now addressed by the
product design team. -->
- [x] Changes file added for user-visible changes in `changes/`,
`orbit/changes/` or `ee/fleetd-chrome/changes`.
See [Changes
files](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/guides/committing-changes.md#changes-files)
for more information.
- [x] Input data is properly validated, `SELECT *` is avoided, SQL
injection is prevented (using placeholders for values in statements)
- [x] Added/updated automated tests
- [x] Manual QA for all new/changed functionality
7c2c6736cc