Create new crate in workspace that runs more extensive locally generated test

We currently run a test on locally generated cases of decodecorpus files. This should be moved to another crate in the workspace so these do not have to run on every call to cargo test.

This could also contain more tests that ensure correctness with big corpuses of data, like for dicts, compression etc ect

Start by locating the existing test for locally generated decodecorpus files and inspect the workspace configuration. Move that test into a separate crate so it no longer runs with every cargo test invocation, then verify the regular and new test commands and consider coverage for large dict and compression corpuses.

Written by the indexing model from the issue text.