Implement `CodeBuilder` bindings

[igamigo]

Once 0xMiden/miden-base#2142 is done, we can implement CodeBuilder on the WebClient to streamline parsing MASM code into different objects.
We currently already have ScriptBuilder, so in practice this just means:

• Replacing the inner struct and renaming where applicable
• Removing the WebClient's ScriptBuilder external assembler (was only kept for being able to provide support for building AccountCode)
• We should review the APIs so that it reflects the upstream better, and maybe we can remove the AccountComponent::compile