Support deno <script>

[bartlomieju]

This is a long standing issue and there's a lot of desire for this change in the core team.

Instead of deno run script.ts, we would like to be able to do deno script.ts.

The permissions flags and other CLI options are preserved - so to run with all permissions
one can do deno -A script.ts.

This will require some intricate acrobatics with Clap in cli/args/flags.rs, so it's best if one of the
core team members works on this.

Related #24450