Add ability to inject scriptlets according to origin of ancestor contexts (uBO)

https://github.com/gorhill/uBlock/commit/a483f7955fc8c9c820684c3f55c9f982a7abb2d3

I think that in an AdGuard filter, we can write it like
```adblock
example.com>>#%#//scriptlet('set-constant', 'iAmEmbeddedInExampleDotCom', 'true')
```