Add new scriptlet — append/load scripts

[AdamWr]

Sometimes apps cannot detect source of the request, so we need a scriptlet which we load these scripts, so source will be detected.

For example here - AdguardTeam/AdguardFilters#110659
Source of connatix.com script is not detected, so we cannot easily fix it with apps.

Screenshot

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Another case - AdguardTeam/AdguardFilters#109135
After clicking on "Produkt bewerten" button, mpsnare.iesnare.com/snare.js is loaded and source is not detected.

Screenshot

[ameshkov]

Actually, I think this is a wrong place to solve this kind of issues. We're trying to fix CoreLibs bug in Scriptlets which are used in all products.

Here's a better alternative solution:
AdguardTeam/CoreLibs#135 (comment)

@AdamWr could you please add similar examples to that CL issue?

[AdamWr]

Unfortunately, currently I don't have any other examples, but if I will find something then I will add it to mentioned issue.