This commit adds alternate dispatch method to core JS API.
"Deno.core.dispatchByName()" works like "Deno.core.dispatch()",
but takes op name instead of op id as a first argument.
This commits add two new methods to "Deno.core" namespace: "encode" and "decode".
Those methods are bound in Rust to provide a) fast b) generally available of encoding and decoding UTF-8 strings.
Both methods are now used in "cli/js/dispatch_json.ts".
Following JS ops were moved to separate files in cli/js/ops directory:
- compiler
- dispatch_json
- dispatch_minimal
- errors
- fetch
- fs_events
- os
- random
- repl
- resources
- runtime_compiler
- runtime
- tty
