feat: cross device integration test

[Zicchio]

This includes an initial implementation of cross device test, which closes #247

This is a brief description of the proposed solution:

1. overall approach is similar to same device test
2. cookies and responses are updated to reflect the expectations of the cross device flow
3. after each authentication step in the flow, a second request.Session check(s) that the status endpoint yields the expected status code and message

Step 3 is non trivial as it requires obtaining somehow the status endpoint and its query parameters. This is done by parsing the Qr code page (pre authn endpoint), which is, frankly put, bad design... but I can't think of a better solution. Alternatives and proposals are welcomed
https://github.com/Zicchio/eudi-wallet-it-python/blob/bcd4593cf69070a649ba8573c407bc111a6e7628/example/satosa/integration_test/cross_device_integration_test.py#L46-L57

This is NOT in scope of this PR:

1. unified design/code for both tests; a minor refactoring that involves the same device flow should follow this PR; this was not done here in order to minimize possible conflicts with other concurrent PRs that are validated with the same device flow (paraphrasing: by design there are no changes to https://github.com/Zicchio/eudi-wallet-it-python/blob/bcd4593cf69070a649ba8573c407bc111a6e7628/example/satosa/integration_test/main.py).
2. possible invocation with an automated testing tool
3. integration of the test in the CI pippeline (afaik same device flow is also not involved in the CI pipeline)