SDK-2314

Each environment now has a separate file which stores its canister ID mappings (canister name -> canister ID).

The file locates at .icpdata/{env}.ids.json by default.

For example, after creating canister "my-canister" to an environment named "my-environment", the file .icpdata/my-environment.ids.json will be created with following content:

{
  "my-canister": "tqzl2-p7777-77776-aaaaa-cai"
}

Users are encouraged to commit such generated files to VCS so that the created canister IDs won't get lost.
Therefore, they are stored in a different directory other than .icp which is normally ignored.

Test

The ID mappings file is asserted to be existed at the end of canister_create test in canister_create_tests.rs.