seal_reentrant_count returns contract reentrant count (#12695)

* Add logic, test, broken benchmark

* account_entrance_count

* Addressing comments

* Address @agryaznov's comments

* Add test for account_entrance_count, fix ci

* Cargo fmt

* Fix tests

* Fix tests

* Remove delegated call from test, address comments

* Minor fixes and indentation in wat files

* Update test for account_entrance_count

* Update reentrant_count_call test

* Delegate call test

* Cargo +nightly fmt

* Address comments

* Update reentrant_count_works test

* Apply weights diff

* Add fixture descriptions

* Update comments as suggested

* Update reentrant_count_call test to use seal_address

* add missing code

* cargo fmt

* account_entrance_count -> account_reentrance_count

* fix tests

* fmt

* normalize signatures

Co-authored-by: yarikbratashchuk <yarik.bratashchuk@gmail.com>

substrate/frame/contracts/src/exec.rs

@@ -296,6 +296,15 @@ pub trait Ext: sealing::Sealed {
 
 	/// Sets new code hash for existing contract.
 	fn set_code_hash(&mut self, hash: CodeHash<Self::T>) -> Result<(), DispatchError>;
+
+	/// Returns the number of times the currently executing contract exists on the call stack in
+	/// addition to the calling instance. A value of 0 means no reentrancy.
+	fn reentrant_count(&self) -> u32;
+
+	/// Returns the number of times the specified contract exists on the call stack. Delegated calls
+	/// are not calculated as separate entrance.
+	/// A value of 0 means it does not exist on the call stack.
+	fn account_reentrance_count(&self, account_id: &AccountIdOf<Self::T>) -> u32;
 }
 
 /// Describes the different functions that can be exported by an [`Executable`].
@@ -1374,6 +1383,17 @@ where
 		);
 		Ok(())
 	}
+
+	fn reentrant_count(&self) -> u32 {
+		let id: &AccountIdOf<Self::T> = &self.top_frame().account_id;
+		self.account_reentrance_count(id).saturating_sub(1)
+	}
+
+	fn account_reentrance_count(&self, account_id: &AccountIdOf<Self::T>) -> u32 {
+		self.frames()
+			.filter(|f| f.delegate_caller.is_none() && &f.account_id == account_id)
+			.count() as u32
+	}
 }
 
 mod sealing {