Fixes #4879
This commit removes Deno.OpenMode along with overloaded variants of Deno.open() and Deno.openSync() that used OpenMode.
This ensures the deno executable is properly created before running the integration tests. Also allows deno_cli to be used as a lib. Docs are now properly generated: https://docs.rs/deno_cli/0.18.4/deno_cli/ Towards #2933 Prep for #2955