feat: compute pallet/storage prefix hash at compile time (#1539)

Since the hash rules of this part of the `pallet_prefix/storage_prefix`
are always fixed, we can put the runtime calculation into compile time.

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polkadot address: 15ouFh2SHpGbHtDPsJ6cXQfes9Cx1gEFnJJsJVqPGzBSTudr

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Co-authored-by: Juan <juangirini@gmail.com>
Co-authored-by: command-bot <>
Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

substrate/frame/support/procedural/src/pallet/mod.rs

@@ -26,7 +26,7 @@
 //!   to user defined types. And also crate new types and implement block.
 
 mod expand;
-mod parse;
+pub(crate) mod parse;
 
 pub use parse::{composite::keyword::CompositeKeyword, Def};
 use syn::spanned::Spanned;