Add .cargo/config.toml to spacetime init Rust project with default target to wasm

[mamcx]

Description of Changes

Closes #1730.

Now when spacetimedb-cli init --lang rust it will create the config that pin target = "wasm32-unknown-unknown".

Also, I added the config to all the modules for completion.

API and ABI breaking changes

1

It actually fix the generated project.

Expected complexity level and risk

1

Testing

• [x] Confirm the issue calling manually cargo build before and after this patch.

[bfops]

(Except that this is failing Internal tests)

[jdetter]

Unassigned myself because Zeke has reviewed