Drop the no-std feature from BP and drop feature implications

Now that we don't have to have everything in our entire ecosystem
use the same `std`/`no-std` feature combinations we should start by
untangling our own features a bit.

This takes the first step by removing the `no-std` feature entirely
from the `lightning-background-processor` crate and removing all
feature implications on dependencies from the remaining `std`
feature.

It also addresses a CI oversight where we were not testing
`lightning-background-processor` without the `std` feature in CI at
all.

Author: TheBlueMatt

ci/ci-tests.sh

@@ -60,6 +60,7 @@ fi
 
 echo -e "\n\nTest futures builds"
 cargo test -p lightning-background-processor --verbose --color always --features futures
+cargo test -p lightning-background-processor --verbose --color always --features futures --no-default-features
 
 echo -e "\n\nTest Custom Message Macros"
 cargo test -p lightning-custom-message --verbose --color always

lightning-background-processor/Cargo.toml

@@ -15,8 +15,7 @@ rustdoc-args = ["--cfg", "docsrs"]
 
 [features]
 futures = [ ]
-std = ["bitcoin/std", "lightning/std", "lightning-rapid-gossip-sync/std"]
-no-std = ["lightning/no-std", "lightning-rapid-gossip-sync/no-std"]
+std = []
 
 default = ["std"]