splitup the `scram_over_mtls` module.

[rukai]

blocked on https://github.com/shotover/shotover-proxy/pull/1654

Split the scram_over_mtls module up to have 2 new submodules:

• recreate_token_queue module should include:
  • The RecreateTokenQueue struct and its methods
  • The TokenToRecreate struct and its methods
• create_token module should include:
  • the create_token_with_timeout function
  • the find_new_brokers function
  • the create_delegation_token_for_user function
  • the wait_until_delegation_token_ready_on_all_brokers function
  • the is_delegation_token_ready function

The new file structure will look like:

• scram_over_mtls.rs
• scram_over_mtls/recreate_token_queue.rs
• scram_over_mtls/create_token.rs

Make sure to include:

mod recreate_token_queue;
mod create_token;

in scram_over_mtls.rs to import the 2 submodules.