add regex flags option

[jhonny111s]

when we want to replace a text, it is very useful to be able to use the flags of a regex, for example to use insensitive case

new RegExp('pattern', 'flags');

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions#advanced_searching_with_flags

{
  "name": "my-awesome-package",
  "auto-changelog": {
    "replaceText": {
      "(ABC-\\d+)": "[`$1`](https://issues.apache.org/jira/browse/$1)"
    },
    "flags": "i"
  }
}

[ljharb]

should this throw if flags is not a string or undefined?

[jhonny111s]

no, keep the default behavior if those conditions are not met

[ljharb]

why would we want to silently ignore bad input?

[jhonny111s]

@cookpete what do you think?

[jhonny111s]

@ljharb I wanted to keep the default behavior, what do you suggest?

[ljharb]

If someone is passing a flags option, they're already at risk of breakage if they're passing a string, so I don't think we need to worry about that.