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
* Compiler no longer has its own Tokio runtime. Compiler handles one
message and then exits.
* Uses the simpler ts.CompilerHost interface instead of
ts.LanguageServiceHost.
* avoids recompiling the same module by introducing a hacky but simple
`hashset<string>` that stores the module names that have been already
compiled.
* Removes the CompilerConfig op.
* Removes a lot of the mocking stuff in compiler.ts like `this._ts`. It
is not useful as we don't even have tests.
* Turns off checkJs because it causes fmt_test to die with OOM.
