Add bitvec-like generic support to the scale-bits type for use in codegen (#718)

* Add bitvec-like generic support to the scale-bits type for use in codegen

* Use nightly 1.66 formatting

* Fix reading input while decoding bit sequences

* Add tests for our DecodedBits wrapper

* Add convenience DecodedBits::(in)to_bits functions

* Don't expose DecodedBits::bit_format

* Re-export scale_bits as peer dependency

* Move subxt::utils into a separate file

* Hide DecodedBits internals

* Don't re-export types from the `bits` module

* Update subxt/src/utils/bits.rs

Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>

* Update subxt/src/utils/bits.rs

Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>

* Address review feedback

* Clarify the byte needed calculation in DecodedBits encoding

* Remove remaining dbg! invocations

Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>

codegen/src/types/tests.rs

@@ -745,10 +745,22 @@ fn generate_bitvec() {
     registry.register_type(&meta_type::<S>());
     let portable_types: PortableRegistry = registry.into();
 
+    let substitutes = [
+        (
+            String::from("bitvec::order::Lsb0"),
+            parse_quote!(::subxt_path::utils::bits::Lsb0),
+        ),
+        (
+            String::from("bitvec::order::Msb0"),
+            parse_quote!(::subxt_path::utils::bits::Msb0),
+        ),
+    ]
+    .into();
+
     let type_gen = TypeGenerator::new(
         &portable_types,
         "root",
-        Default::default(),
+        substitutes,
         DerivesRegistry::new(&"::subxt_path".into()),
         "::subxt_path".into(),
     );
@@ -762,8 +774,8 @@ fn generate_bitvec() {
                 use super::root;
                 #[derive(::subxt_path::ext::codec::Decode, ::subxt_path::ext::codec::Encode, Debug)]
                 pub struct S {
-                    pub lsb: ::subxt_path::ext::bitvec::vec::BitVec<::core::primitive::u8, root::bitvec::order::Lsb0>,
-                    pub msb: ::subxt_path::ext::bitvec::vec::BitVec<::core::primitive::u16, root::bitvec::order::Msb0>,
+                    pub lsb: ::subxt_path::utils::bits::DecodedBits<::core::primitive::u8, ::subxt_path::utils::bits::Lsb0>,
+                    pub msb: ::subxt_path::utils::bits::DecodedBits<::core::primitive::u16, ::subxt_path::utils::bits::Msb0>,
                 }
             }
         }

codegen/src/types/type_path.rs

@@ -246,7 +246,7 @@ impl TypePathType {
                 bit_store_type,
                 crate_path,
             } => {
-                let type_path = parse_quote! { #crate_path::ext::bitvec::vec::BitVec<#bit_store_type, #bit_order_type> };
+                let type_path = parse_quote! { #crate_path::utils::bits::DecodedBits<#bit_store_type, #bit_order_type> };
                 syn::Type::Path(type_path)
             }
         }