* Revert "port more ops to JSON (#2809)"

This reverts commit 137f3373.

* Revert "port ops to JSON: compiler, errors, fetch, files (#2804)"

This reverts commit 79f82cf1.

* Revert "Port rest of os ops to JSON (#2802)"

This reverts commit 5b2baa5c.

Similar to React's CONTRIBUTING.md
https://github.com/facebook/react/blob/master/CONTRIBUTING.md

Converts env(), exit(), execPath(), utime() and utimeSync() to use JSON
instead of flatbuffers.

Using a specialized flag rather than the generic 'args' option makes
build_extra/rust/BUILD.gn shorter and more readable.

Fixes #1432

Just some clean up reorganization around flatbuffer/minimal dispatch
code. This is prep for adding a JSON dispatcher.

groupCollapsed alias to group, remove noTrailingNewline, move newline 
out of stringifyArgs, fix console.dir, add tests, and fix a repl log quirk.
For repl logging quirks, I believe we should not indent repl logging. If
we really want such indentation, we probably also want to indent "> "
prompts.

This is causing a segfault for unknown reasons - see #2787.

This reverts commit 498f6ad4.

readSync and writeSync use dispatch_minimal now.

Note cli/dispatch_minimal.rs ops are not yet included in cli/ops.

This is part of work towards #2730

* Propagate Url::to_file_path() errors instead of panicking

Removes the magic number hack to switch between flatbuffers and the
minimal dispatcher.

Adds machinery to pass the op_id through the shared_queue.