Re-export initialize_contract function

[HCastano]

I don't think users should be accessing stuff from the codegen module directly, so this
PR re-exports initialize_contract so it can be used from the ink_lang module instead.

[Robbepop]

I want to keep ink_lang root clean from functionality such as this API.
The reason why I introduced the API to the hidden codegen module is that I do not think that it will be stable for long which is yet another reason we should not be putting this API into ink_lang root before ink! 3.0 stable release.
As a compromise we could put it into a utils submodule of root.

[codecov-commenter]

Codecov Report

Merging #1077 (17fd88d) into master (67b457c) will decrease coverage by 3.47%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #1077      +/-   ##
==========================================
- Coverage   78.70%   75.22%   -3.48%     
==========================================
  Files         253      253              
  Lines        9411     9409       -2     
==========================================
- Hits         7407     7078     -329     
- Misses       2004     2331     +327     

Impacted Files	Coverage Δ
...lang/tests/ui/contract/pass/example-erc20-works.rs	1.51% <0.00%> (ø)
...ang/tests/ui/contract/pass/example-erc721-works.rs	0.67% <0.00%> (ø)
crates/lang/ir/src/ir/contract.rs	0.00% <0.00%> (-100.00%)	⬇️
crates/lang/ir/src/ir/ink_test.rs	0.00% <0.00%> (-87.50%)	⬇️
crates/lang/ir/src/ir/trait_def/mod.rs	0.00% <0.00%> (-66.67%)	⬇️
crates/lang/ir/src/ir/blake2.rs	20.00% <0.00%> (-60.00%)	⬇️
crates/lang/ir/src/ir/trait_def/item/trait_item.rs	45.31% <0.00%> (-43.75%)	⬇️
crates/lang/ir/src/ir/trait_def/config.rs	7.69% <0.00%> (-38.47%)	⬇️
crates/lang/ir/src/ir/utils.rs	53.84% <0.00%> (-30.77%)	⬇️
crates/lang/ir/src/ir/item_mod.rs	62.28% <0.00%> (-27.43%)	⬇️
... and 19 more

---

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[HCastano]

It's unclear if we're gonna keep initialize_contract, so I'm gonna close this

[paritytech-cicd-pr]

🦑 📈 ink! Example Contracts ‒ Changes Report 📉 🦑

These are the results when building the examples/* contracts from this branch with cargo-contract 0.17.0-942c50c and comparing them to ink! master:

	Δ Optimized Size	Δ Used Gas	Total Optimized Size	Total Used Gas
accumulator			1.44 K
adder			2.94 K
contract-terminate			1.31 K	215_704
contract-transfer			8.55 K	15_704
delegator			7.63 K	51_343
dns			10.20 K	47_112
erc1155			28.32 K	94_224
erc20			9.80 K	47_112
erc721			13.70 K	125_632
flipper			1.76 K	15_704
incrementer			1.64 K	15_704
multisig			26.76 K	103_580
proxy			3.87 K	32_304
rand-extension			5.12 K	15_704
subber			2.96 K
trait-erc20			10.10 K	47_112
trait-flipper			1.53 K	15_704
trait-incrementer			1.62 K	31_408

Link to the run | Last update: Tue Feb 15 20:04:37 CET 2022

[HCastano]

Resurrected because use-ink/cargo-contract#431 is moving forward, which looks for instances of initialize_contract

[xgreenx]

Resurrected because paritytech/cargo-contract#431 is moving forward, which looks for instances of initialize_contract

Sorry, I already mention that, but I didn't get any comment=) What do you think about that idea?

It allows us to simplify the definition of the constructor for the user and it also is more intuitive for Solidity developers.