contracts: Add storage deposits (#10082)

* Frame no longer needs to be mutable (refactoring artifact)

* Remove Contract/Tombstone deposit

* Add StorageMeter

* cargo fmt

* Fix weight annotation

* cargo run --quiet --release --features=runtime-benchmarks --manifest-path=bin/node/cli/Cargo.toml -- benchmark --chain=dev --steps=50 --repeat=20 --pallet=pallet_contracts --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --output=./frame/contracts/src/weights.rs --template=./.maintain/frame-weight-template.hbs

* Simplify keep check for contract accounts

- Make sure that the "base deposit" for each contract >= ed
- Remove now obsolete checks when sneding away free balance

* Remove unused imports and functions

* Rename storage_limit to storage_deposit_limit

* cargo fmt

* Fix typo

Co-authored-by: Michael Müller <michi@parity.io>

* Finish up rename of storage_limit

* Fix rpc tests

* Make use of `StorageDepositLimitTooHigh`

* Add tests and fix bugs discovered by tests

* Add storage migration

* Don't use u128 in RPC

* Fix weight of migration

* Rename `endowment` to `value`

* Fix bug where contract couldn't get funded by a storage deposit

- Make sure that contract gets funded from deposits before value is transferred
- Don't reserve value at origin because otherwise funding isn't possible
	- Just transfer free balance and reserve it after the transfer
- When refunding make sure that this refund can't dust the contract
	- Can only happen after a runtime upgrade where costs where upped
- Add more tests

* Apply suggestions from code review

Co-authored-by: Andrew Jones <ascjones@gmail.com>

* Remove unused `fn storage_meter`

* Fix copy pasta doc error

* Import `MaxEncodeLen` from codec

* Beautify RPC trait bounds

* Add re-instrument behaviour to dispatchable doc

* Make sure a account won't be destroyed a refund after a slash

* Apply suggestions from code review

Co-authored-by: Andrew Jones <ascjones@gmail.com>

* Update `Storage::write` docs

* Improve doc

* Remove superflous conditional

* Typos

* Remove superflous clone (refactoring artifact)

* Apply suggestions from code review

Co-authored-by: Andrew Jones <ascjones@gmail.com>

Co-authored-by: Parity Bot <admin@parity.io>
Co-authored-by: Michael Müller <michi@parity.io>
Co-authored-by: Andrew Jones <ascjones@gmail.com>

substrate/frame/contracts/fixtures/drain.wat

@@ -33,7 +33,9 @@
 			)
 		)
 
-		;; Self-destruct by sending full balance to the 0 address.
+		;; Try to self-destruct by sending full balance to the 0 address.
+		;; All the *free* balance will be send away, which is a valid thing to do
+		;; because the storage deposits will keep the account alive.
 		(call $assert
 			(i32.eq
 				(call $seal_transfer
@@ -42,7 +44,7 @@
 					(i32.const 0)	;; Pointer to the buffer with value to transfer
 					(i32.const 8)	;; Length of the buffer with value to transfer
 				)
-				(i32.const 4) ;; ReturnCode::BelowSubsistenceThreshold
+				(i32.const 0) ;; ReturnCode::Success
 			)
 		)
 	)