Close: #3443 

Some tests were silently failing after #3358 and #3434 because pool.spawn_ok
was used which doesn't panic on errors. For reference, the failure looked like this:

thread '<unnamed>' panicked at 'assertion failed: match isolate.poll_unpin(cx) { Poll::Ready(Ok(_)) => true, _ => false, }', core/isolate.rs:1408:7

Preventing release v0.26.0
This reverts commit 81efa9d9.

Fixes: #3440
Fixes: #3153

It seems this has caused CI to go red for an unknown reason.

This reverts commit 866dba8a.

- Remove ability to specify run arguments like `--allow-net` after the
  script argument. It's too hacky to make work with clap.
- Remove `--v8-options`, instead use `--v8-flags=--help`
- Give more descriptive names to unit tests in flags.rs
- Assume argv and subcommand into DenoFlags struct so the output of
  flags module is only DenoFlags rather than the tuple (subcommand, flags,
  argv).
- Improve CLI help text
- Make `deno run` specific args like `--allow-net` only show up in 'deno
  help run' instead of as global flags in `deno help`.
- Removes `deno version` to simplify our implementation and be closer to
  clap defaults. `deno -V` now only shows Deno's version and not V8's nor
  TypeScript. `Deno.versions` can be used to see that information.
- Prevent clap from auto-detecting terminal width and attempting to wrap
  text.

This PR removes tokio_util::block_on - refactored compiler and file 
fetcher slightly so that we can safely block there - that's because 
only blocking path consist of only synchronous operations.

Additionally I removed excessive use of tokio_util::panic_on_error 
and tokio_util::run_in_task and moved both functions to cli/worker.rs, 
to tests module.

Closes #2960