Publish `merge-toml` as a crate instead of copying code

Currently `bottlerocket/agents/src/userdata.rs` contains a lot of code from the `merge-toml` crate found here: https://github.com/bottlerocket-os/bottlerocket/blob/v1.11.1/sources/api/storewolf/merge-toml/src/lib.rs. Instead of copying this code, the `merge-toml` crate should be published to `crates.io` so it can be used as a dependency in TestSys.

Compare bottlerocket/agents/src/userdata.rs with the merge-toml implementation in sources/api/storewolf/merge-toml/src/lib.rs. Start by determining the crate's publishing requirements and how TestSys should consume it as a dependency. Done means the copied implementation is replaced by the published crates.io dependency and TestSys continues to use the same functionality.

Written by the indexing model from the issue text.