Support blocking web bundles in MV2

Background

Igalia evaluated web bundles support by our webext-sdk in an MV2 context. All the background and details on what exactly they did can be found in this ticket. Please ping me on Mattermost if you still don't have access. It seems that our SDK does currently not support blocking a whole web bundle.
The Google ads team plans to roll out web bundles end of Q1, we may be able to negotiate the end of April with them. But we need to consider that the change needs to land in our web extensions by then, not just in the SDK. @d.rebeschini will talk to @lursachi about the exact timeline for a release. But this makes the task an immediate priority for us.

Use case

If web bundles will be rolled out, we may want to block the whole bundle instead of the individual subresources.

What to change

Support blocking the resource type web bundle in our SDK.

Release notes

• Release notes added