refactor(repo): move all crates into crates folder

[drahnr]

Moves all rust crates into a joint crates folder, binding is moved out from contracts into crates as contract-bindings, fendermint becomes client

This change is 

[karlem]

1. The Docker image build is failing.
2. There are still references to "fendermint" in a few places in the codebase. The PR description should mention that we are renaming "fendermint" to "client."
3. I would abstain from committing the generated bindings into Git and instead have them generated as part of the Cargo build process or something similar.

[drahnr]

There are still references to "fendermint" in a few places in the codebase. The PR description should mention that we are renaming "fendermint" to "client."

I cannot rename all of fendermint right now, since we still produce a binary named fendermint and APIs. This will be part of a larger type rename series, doing this now will hurt too much. I am also not sold on client, so if you think node is bettter, happy to adjust.

[raulk]

I think "client" is ambiguous because it's a relative term -- "a client of what?" Would prefer "node"

[karlem]

@drahnr I agree with the rename from client to node, but there are still some references to client left. I suggest searching for client/.

[karlem]

LGT, but the CI needs to be fixed first. Build is failing.