resources: Remove baked in resources (#36042)

This allows removing a LazyLock around the resources.
We override the baked in resources unconditionally in servoshell
upon initialization anyway
([desktop](9f93ccd942/ports/servoshell/desktop/cli.rs (L15)),
[android](9f93ccd942/ports/servoshell/egl/android/simpleservo.rs (L49)),
[ohos](9f93ccd942/ports/servoshell/egl/ohos/simpleservo.rs (L43))
), meaning that the baked in resources
are unused in servoshell.

For 3rd-party embedders, we probably also want to the let them know
early that they should initialize the resources, instead of
restricting the panics to production mode.

Rippy is the only resource which was required. Since it is only
253 bytes large, we just bake that resource in as a fallback.

We do want to make using the resources easy from tests, so we add
some logic to keep the baked in resources for tests only and initialize
the resource reader on first access.

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Signed-off-by: Jonathan Schwender <schwenderjonathan@gmail.com>

components/shared/net/Cargo.toml

@@ -40,3 +40,6 @@ servo_rand = { path = "../../rand" }
 servo_url = { path = "../../url" }
 url = { workspace = true }
 uuid = { workspace = true }
+
+[dev-dependencies]
+embedder_traits = { workspace = true, features = ["baked-default-resources"] }