Gracefully returning DNR for unsupported redirect resources

[seia-soto]

Currently, AdGuard converter doesn't allow using unlisted redirect resource in $redirect filters. outbrain-widget.js is supported by uBlock Origin but it's not listed in their supported redirect names: https://github.com/AdguardTeam/Scriptlets/blob/master/wiki/about-redirects.md#redirect-resources

As a result, the converter throws an error:

DNR: Error during creating indexed rule with hash: Cannot create IRule from filter "0" and line "1": "$redirect modifier is invalid" in the rule: "||widgets.outbrain.com/outbrain.js^$domain=allocine.fr,redirect=outbrain-widget.js"

Gracefully returning value would be preferred in these kinds of situations.

One possible idea is, we can replace a value of $redirect to noopjs temporarily then rollback after the conversion.

[seia-soto]

Also, if we're going to ship our own resource surrogates in the future, this is necessary.