[Feature #20329] Separate additional flags from main dump options

Additional flags are comma separated list preceeded by `-` or `+`.

Before:
```sh
$ ruby --dump=insns+without_opt
```

After:
```sh
$ ruby --dump=insns-opt,-optimize
```

At the same time, `parsetree_with_comment` is split to `parsetree`
option and additional `comment` flag.

Before:
```sh
$ ruby --dump=parsetree_with_comment
```

After:
```sh
$ ruby --dump=parsetree,+comment
```

Also flags can be separate `--dump`.
```sh
$ ruby --dump=parsetree --dump=+comment --dump=+error_tolerant
```

Ineffective flags are ignored silently.
```sh
$ ruby --dump=parsetree --dump=+comment --dump=+error_tolerant
```

0 files changed, 0 insertions, 0 deletions