Fix default providers query direction

[deem0n]

MiApplication>>defaultProvidersQuery currently evaluates allClients, so a Butterfly map using the default settings shows incoming clients on both sides. For a chain client → central → provider, the right-hand providers query incorrectly returns client.

Change the providers query to evaluate allProviders; leave defaultClientsQuery unchanged. Add a regression test using real Famix Smalltalk methods and invocations to assert both query directions.

Validation in an isolated Moose 13 / Pharo 13 image:

• The new regression test fails with the original implementation (one failure, no errors).
• With the fix, MiApplicationTest, MiButterflyMapModelTest, and MiButterflyMapBrowserTest report 50 passed, two skipped, no failures or errors.
• git diff --check passes.

Discovered while visualizing a PostgreSQL FAMIX model; the fix and test are independent of FAMIXNGSQL. Fork CI could not be dispatched because GitHub has not exposed the fork's workflows; upstream CI results are pending.