Make seal_ecdsa test cases differ from the ones used in the pallet

[agryaznov]

I suggest testing those ones versus different public keys in pallet_contracts, in doc comments examples in ink! and finally in e2e waterfall tests. By doing this we make the tests independent and more robust.

[paritytech-cicd-pr]

🦑 📈 ink! Example Contracts ‒ Changes Report 📉 🦑

These are the results when building the examples/* contracts from this branch with cargo-contract 1.3.0-cef152e and comparing them to ink! master:

	Δ Optimized Size	Δ Used Gas	Total Optimized Size	Total Used Gas
accumulator			1.04 K
adder			2.13 K
contract-introspection			2.37 K
contract-terminate			0.94 K	275_000
contract-transfer			8.13 K	75_000
data-structures			1.73 K
delegate-calls			2.96 K	76_276
delegator			6.38 K	232_281
dns			8.89 K	225_000
erc1155			17.30 K	450_000
erc20			8.49 K	225_000
erc721			11.82 K	600_000
flipper			1.31 K	75_000
forward-calls			2.88 K	151_427
incrementer			1.21 K
mother			12.41 K
multisig			25.12 K	470_156
rand-extension			3.92 K	75_000
seal-code-hash			1.58 K
seal-ecdsa			1.81 K
set-code-hash			1.57 K	150_000
subber			2.15 K
trait-erc20			8.77 K	225_000
trait-flipper			1.00 K	75_000
trait-incrementer			1.19 K	150_000
updated-incrementer			9.62 K
upgradeable-flipper			1.55 K

Link to the run | Last update: Fri May 20 16:56:30 CEST 2022

[codecov-commenter]

Codecov Report

Merging #1268 (d3fa1fb) into master (3c267d6) will increase coverage by 0.23%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1268      +/-   ##
==========================================
+ Coverage   78.48%   78.72%   +0.23%     
==========================================
  Files         227      228       +1     
  Lines        8645     8675      +30     
==========================================
+ Hits         6785     6829      +44     
+ Misses       1860     1846      -14     

Impacted Files	Coverage Δ
crates/env/src/api.rs	33.80% <ø> (ø)
crates/lang/src/env_access.rs	12.00% <ø> (ø)
...rates/storage/src/collections/binary_heap/tests.rs	93.33% <0.00%> (-2.23%)	⬇️
crates/lang/ir/src/ir/attrs.rs	81.99% <0.00%> (-0.28%)	⬇️
crates/allocator/src/bump.rs	0.00% <0.00%> (ø)
crates/engine/src/ext.rs	70.17% <0.00%> (+14.03%)	⬆️
crates/engine/src/test_api.rs	91.20% <0.00%> (+18.68%)	⬆️
crates/engine/src/chain_extension.rs	42.85% <0.00%> (+23.80%)	⬆️

---

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