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/restoration.wat

@@ -1,5 +1,6 @@
 (module
 	(import "env" "ext_set_storage" (func $ext_set_storage (param i32 i32 i32)))
+	(import "env" "ext_input" (func $ext_input (param i32 i32)))
 	(import "env" "ext_restore_to"
 		(func $ext_restore_to
 			(param i32 i32 i32 i32 i32 i32 i32 i32)
@@ -7,7 +8,25 @@
 	)
 	(import "env" "memory" (memory 1 1))
 
+	(func $assert (param i32)
+		(block $ok
+			(br_if $ok
+				(get_local 0)
+			)
+			(unreachable)
+		)
+	)
+
 	(func (export "call")
+		;; copy code hash to contract memory
+		(call $ext_input (i32.const 264) (i32.const 304))
+		(call $assert
+			(i32.eq
+				(i32.load (i32.const 304))
+				(i32.const 32)
+			)
+		)
+
 		(call $ext_restore_to
 			;; Pointer and length of the encoded dest buffer.
 			(i32.const 256)
@@ -49,12 +68,11 @@
 	;; Address of bob
 	(data (i32.const 256) "\02\00\00\00\00\00\00\00")
 
-	;; Code hash of SET_RENT
-	(data (i32.const 264)
-		"\ab\d6\58\65\1e\83\6e\4a\18\0d\f2\6d\bc\42\ba\e9"
-		"\3d\64\76\e5\30\5b\33\46\bb\4d\43\99\38\21\ee\32"
-	)
+	;; [264, 296) Code hash of SET_RENT (copied here by ext_input)
 
-	;; Rent allowance
+	;; [296, 304) Rent allowance
 	(data (i32.const 296) "\32\00\00\00\00\00\00\00")
+
+	;; [304, 308) Size of SET_RENT buffer
+	(data (i32.const 304) "\20")
 )