[TASK] Reorganize tests

[guruvamsi-policharla]

The tests could be organized better. Currently, we have them spread across dist-primitives/examples and individual modules such as dist-primitives/dfft/tests.rs. This was an artifact of the original zksaas repo needing a shell script to enable networking.

Given that we are no longer constrained by this, we can place all of the tests within individual modules -- dfft/dmsm/dpp and get rid of dist-primitives/examples entirely.

Also, dist-primitives/examples/dfft_test.rs is redundant in light of the more extensive set of tests in dist-primitives/dfft/tests.rs.