seal: Rework contracts API (#6573)

* Transition getter functions to not use scratch buffer

* Remove scratch buffer from ext_get_storage

* Remove scratch buffer from ext_call

* Remove scratch buffer from ext_instantiate

* Add ext_input and remove scratch buffer

* Rework error handling (changes RPC exposed data)

* ext_return passes a flags field instead of a return code
	* Flags is only for seal and not for the caller
	* flags: u32 replaced status_code: u8 in RPC exposed type
* API functions use a unified error type (ReturnCode)
* ext_transfer now traps on error to be consistent with call and instantiate

* Remove the no longer used `Dispatched` event

* Updated inline documentation

* Prevent skipping of copying the output for getter API

* Return gas_consumed from the RPC contracts call interface

* Updated COMPLEXTITY.md

* Rename ext_gas_price to ext_weight_to_fee

* Align comments with spaces

* Removed no longer used `ExecError`

* Remove possible panic in `from_typed_value`

* Use a struct as associated data for SpecialTrap::Return

* Fix nits in COMPLEXITY.md

* Renamed SpecialTrap to TrapReason

* Fix test

* Finish renaming special_trap -> trap_reason

* Remove no longer used get_runtime_storage

* fixup! Remove no longer used get_runtime_storage

* Removed tabs for comment aligment

substrate/frame/contracts/fixtures/self_destruct.wat

@@ -1,11 +1,25 @@
 (module
-	(import "env" "ext_scratch_size" (func $ext_scratch_size (result i32)))
-	(import "env" "ext_scratch_read" (func $ext_scratch_read (param i32 i32 i32)))
-	(import "env" "ext_address" (func $ext_address))
-	(import "env" "ext_call" (func $ext_call (param i32 i32 i64 i32 i32 i32 i32) (result i32)))
+	(import "env" "ext_input" (func $ext_input (param i32 i32)))
+	(import "env" "ext_address" (func $ext_address (param i32 i32)))
+	(import "env" "ext_call" (func $ext_call (param i32 i32 i64 i32 i32 i32 i32 i32 i32) (result i32)))
 	(import "env" "ext_terminate" (func $ext_terminate (param i32 i32)))
 	(import "env" "memory" (memory 1 1))
 
+	;; [0, 8) reserved for $ext_address output
+
+	;; [8, 16) length of the buffer
+	(data (i32.const 8) "\08")
+
+	;; [16, 24) Address of django
+	(data (i32.const 16) "\04\00\00\00\00\00\00\00")
+
+	;; [24, 32) reserved for output of $ext_input
+
+	;; [32, 36) length of the buffer
+	(data (i32.const 32) "\04")
+
+	;; [36, inf) zero initialized
+
 	(func $assert (param i32)
 		(block $ok
 			(br_if $ok
@@ -22,36 +36,32 @@
 		;; This should trap instead of self-destructing since a contract cannot be removed live in
 		;; the execution stack cannot be removed. If the recursive call traps, then trap here as
 		;; well.
-		(if (call $ext_scratch_size)
+		(call $ext_input (i32.const 24) (i32.const 32))
+		(if (i32.load (i32.const 32))
 			(then
-				(call $ext_address)
+				(call $ext_address (i32.const 0) (i32.const 8))
 
 				;; Expect address to be 8 bytes.
 				(call $assert
 					(i32.eq
-						(call $ext_scratch_size)
+						(i32.load (i32.const 8))
 						(i32.const 8)
 					)
 				)
 
-				;; Read own address into memory.
-				(call $ext_scratch_read
-					(i32.const 16)	;; Pointer to write address to
-					(i32.const 0)	;; Offset into scratch buffer
-					(i32.const 8)	;; Length of encoded address
-				)
-
 				;; Recursively call self with empty input data.
 				(call $assert
 					(i32.eq
 						(call $ext_call
-							(i32.const 16)	;; Pointer to own address
+							(i32.const 0)	;; Pointer to own address
 							(i32.const 8)	;; Length of own address
 							(i64.const 0)	;; How much gas to devote for the execution. 0 = all.
-							(i32.const 8)	;; Pointer to the buffer with value to transfer
+							(i32.const 36)	;; Pointer to the buffer with value to transfer
 							(i32.const 8)	;; Length of the buffer with value to transfer
 							(i32.const 0)	;; Pointer to input data buffer address
 							(i32.const 0)	;; Length of input data buffer
+							(i32.const 4294967295) ;; u32 max sentinel value: do not copy output
+							(i32.const 0) ;; Length is ignored in this case
 						)
 						(i32.const 0)
 					)
@@ -60,13 +70,11 @@
 			(else
 				;; Try to terminate and give balance to django.
 				(call $ext_terminate
-					(i32.const 32)	;; Pointer to beneficiary address
+					(i32.const 16)	;; Pointer to beneficiary address
 					(i32.const 8)	;; Length of beneficiary address
 				)
 				(unreachable) ;; ext_terminate never returns
 			)
 		)
 	)
-	;; Address of django
-	(data (i32.const 32) "\04\00\00\00\00\00\00\00")
 )