Clarify optimization comment in Cargo.toml (and bump deps to -O2)

The comment in `Cargo.toml` explaining our test optimization was
somewhat incorrect - `[profile.dev]` actually already only applies
to dependencies, so we were already leaving workspace crates
unoptimized with dependencies optimized.

At least, I think we were, but its somewhat unclear whether we were
optimizing the `lightning` crate when it was a dependency of other
workspace crates. So to clarify and ensure we have that behavior,
`[profile.dev]` was swapped for `[profile.dev.package."*"]`.

Finally, because its a slight win for developers, the `opt-level`
on dependencies was set to O2 instead of O1.

Author: TheBlueMatt

Cargo.toml

@@ -13,14 +13,12 @@ exclude = [
     "no-std-check",
 ]
 
-# Our tests do actual crypo and lots of work, the tradeoff for -O1 is well worth it.
-# Ideally we would only do this in profile.test, but profile.test only applies to
-# the test binary, not dependencies, which means most of the critical code still
-# gets compiled as -O0. See
+# Our tests do actual crypo and lots of work, the tradeoff for -O1 is well
+# worth it. Note that we only apply optimizations to dependencies, not workspace
+# crates themselves.
 # https://doc.rust-lang.org/cargo/reference/profiles.html#profile-selection
-[profile.dev]
-opt-level = 1
-panic = "abort"
+[profile.dev.package."*"]
+opt-level = 2
 
 [profile.release]
 opt-level = 3