Migrate to web_accessible_resources and scriptlets.js

[antonok-edm]

Closes brave/brave-browser#4564

With the deprecation of the resources.txt file, this allows adblock-rust to pull resources from uBlock Origin's newer web_accessible_resources directory and scriptlets.js file. Redirectable resources from web_accessible_resources and resources for cosmetic injection from scriptlets.js can both be represented as Resource structs.

Snippet from src/resources.rs:

/// Struct representing a resource that can be used by an adblocking engine.
///
/// - `name`: Represents the primary name of the resource, often a filename
/// - `aliases`: Represents secondary names that can be used to access the resource
/// - `kind`: How to interpret the resource data within `content`
/// - `content`: The resource data, encoded using standard base64 configuration
pub struct Resource {
    pub name: String,
    pub aliases: Vec<String>,
    pub kind: ResourceType,
    pub content: String,
}

/// Different ways that the data within the `content` field of a `Resource` can be interpreted.
///
/// - `Mime(type)` - interpret the data according to the MIME type represented by `type`
/// - `Template` - interpret the data as a Javascript scriptlet template, with embedded template parameters in the form of `{{1}}`, `{{2}}`, etc.
pub enum ResourceType {
    Mime(MimeType),
    Template,
}

pub enum MimeType {
    ImageGif,
    TextHtml,
    ApplicationJavascript,
    AudioMp3,
    VideoMp4,
    ImagePng,
    TextPlain,
    Unknown,
}

The resulting Resources can be loaded into the engine directly, or serialized to JSON for transfer to another instance. The equivalent data structures in JSON are as follows:

// Resource
{
    "name": String,
    "aliases": String[],
    "kind": ResourceType,
    "content": String,
}

// ResourceType
{ "mime": MimeType } | "template"

// MimeType
"image/gif" | "text/html" | "application/javascript" | ... | "application/octet-stream"

A new Javascript function uBlockResources is exposed through adblock-rust's neon bindings. This function takes 3 string arguments, namely:

• The path to uBlock Origin's web_accessible_resources directory
• The path to uBlock Origin's redirect-engine.js file
• The path to uBlock Origin's scriptlets.js file

and will return a list of corresponding Resource JavaScript objects. In combination with a locally checked out version of the uBlock Origin source repo, this function can be used to produce a new set of resources for the adblocking engine.

[AndriusA]

looks good to me, one nit on the data structure for resource lookup

also given the complexity of resource handling has also grown we might want to separate it into a submodule instead of having a bunch of them at the top level

[AndriusA]

lgtm