fix: exception of script injection not respecting aliases

[seia-soto]

fixes #4058

This PR adds:

• public resolveScriptlet to expose private scriptletsByName and the scriptlet objects (we need another method since public getScriptlet returns fully compiled scriptlet) in resources
• public getScriptletSelector(resolver: (name: string) => string | undefined): string to normalise the selectors of script inject cosmetic filters in cosmetic filters

The approach comes with not to add dependency to CosmeticFilter and not to halt existing properties of Resources (including private ones).