Refactor forked provider backend APIs (#1944)

# Description

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## Related issue

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## Tests

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- [ ] Yes
- [ ] No, because they aren't needed
- [ ] No, because I need help

## Added to documentation?

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- [ ] README.md
- [ ] [Dojo Book](https://github.com/dojoengine/book)
- [ ] No documentation needed

## Checklist

- [ ] I've formatted my code (`scripts/prettier.sh`, `scripts/rust_fmt.sh`, `scripts/cairo_fmt.sh`)
- [ ] I've linted my code (`scripts/clippy.sh`, `scripts/docs.sh`)
- [ ] I've commented my code
- [ ] I've requested a review after addressing the comments

bin/katana/src/args.rs

@@ -203,7 +203,7 @@ pub struct EnvironmentOptions {
 
 impl KatanaArgs {
     pub fn init_logging(&self) -> Result<(), Box<dyn std::error::Error>> {
-        const DEFAULT_LOG_FILTER: &str = "info,executor=trace,forked_backend=trace,server=debug,\
+        const DEFAULT_LOG_FILTER: &str = "info,executor=trace,forking::backend=trace,server=debug,\
                                           katana_core=trace,blockifier=off,jsonrpsee_server=off,\
                                           hyper=off,messaging=debug,node=error";
 

crates/katana/storage/provider/src/error.rs

@@ -106,7 +106,7 @@ pub enum ProviderError {
     /// [ForkedProvider](crate::providers::fork::ForkedProvider).
     #[cfg(feature = "fork")]
     #[error(transparent)]
-    ForkedBackend(#[from] crate::providers::fork::backend::ForkedBackendError),
+    ForkedBackend(#[from] crate::providers::fork::backend::BackendError),
 
     /// Any error that is not covered by the other variants.
     #[error("soemthing went wrong: {0}")]