Implement sriHashesStrategy for CSPOptions

[castarco]

As it can be seen in

astro-shield/@kindspells/astro-shield/src/main.d.ts

Line 49 in da0467e

// sriHashesStrategy?: 'all' | 'perPage' // TODO: Enable in the future

We intend to implement a feature to decide how "specific" we are at the time of loading SRI hashes into our CSP headers.

The goal of this feature is to allow the developers to decide whether they want to minimise the size of their CSP headers, or to ensure compatibility with the new View Transitions feature (which can cause some problems if the loaded pages after transition bring into scope new scripts/stylesheets that were not allowed by the CSP header).