[ENG-4075](https://stacklet.atlassian.net/browse/ENG-4075)

### what

support selecting an identity provider in `auto-configure` when the server
reports multiple.
If multiple IDPs are detected, the `--idp` option is required to pick one.

### why

Allow logging in when multiple IDPs are configured in platform.

### testing

tested against my sandbox with the corresponding platform change

### docs

n/a

### what

use the "saml_provider" config key to find the IDP list, fallback to the
old "saml" one for now

### why

the new key will eventually replace the other one

### testing

tested in sandbox

### docs

n/a

### what

 - Update dependencies with security fixes
 - Update versions in .tool-versions to match what is in use elsewhere
- Update flake8 version in pre-commit config to fix py3.12
incompatibility
 - Update test suite to adapt to new version of moto
 - Update pyproject.toml for modern poetry

### why

Security, consistency.

### testing

`poetry install` and unit tests.

### docs

N/A

### what

Add linting with ruff and deptry

### why

Cleanliness and consistency with other projects

### testing

Running the following `just` targets: `install`, `lint`, `format` and
`test`

### docs

N/A

### what

Make URL and Prefix mutually exclusive. Don't return exit code zero if
things failed.

### why

If you passed both at the same time `prefix` would override the URL, so
for example if you said `--url=console.dev.stacklet.dev` but then also
said `--prefix=dev` it would ignore url and send you to
`console.dev.stacklet.io` which is confusing.

### testing

Added many tests

### docs

The CLI has `--help`

---------

Co-authored-by: John Anderson <john@stacklet.io>