debugger: use option -d for debugger activation

Added `-d` option for activation of debugger shell:
- it calls debugger shell in `luadebug.lua` instead of
  a standard interactive shell from `console.lua`;
- that option complements original way for starting a
  debugging shell via `require 'luadebug'()`, but is a
  little bit easier.

NB! At the moment when we enter debugging mode instead of
a standard Tarantool console, we change banner to:
```
Tarantool debugger 2.11.0-entrypoint-852-g9e6ed28ae
type 'help' for interactive help
```

Part of #7456

@TarantoolBot document
Title: Command-line option `-d` for console debugger.

Please see third_party/lua/README-luadebug.md for a full description
of different ways to activate debugging shell.