fix: add fields for contract filter performance

[zachdaniel]

Resolves #1951

Changelog

Bug Fixes

• Due to poor performance with the filters for not decompiled and not verified smart contracts in the JSON RPC, this adds supporting fields on addresses to signify decompiled/verified contract addresses.
• Adds a Temporary fetcher that will backfill the old data.

Incompatible Changes

• For performance reasons, I had to remove the "DecompilerVersion" attribute from the API response for listing contracts. I can add it back in if necessary, but things will become much slower. Since this was a new API endpoint, I don't think it would be too bad to remove that field. Let me know.

Checklist for your PR

• I added an entry to CHANGELOG.md with this PR
• If I added new functionality, I added tests covering it.
• If I fixed a bug, I added a regression test to prevent the bug from silently reappearing again.
• I checked whether I should update the docs and did so if necessary

[coveralls]

Pull Request Test Coverage Report for Build 240d86fb-4f10-4437-8b44-89a58d69cd0b

• 14 of 22 (63.64%) changed or added relevant lines in 4 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.06%) to 81.062%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
apps/explorer/lib/explorer/chain.ex	6	14	42.86%

Files with Coverage Reduction	New Missed Lines	%
apps/block_scout_web/lib/block_scout_web/views/api/rpc/contract_view.ex	2	88.46%

Totals
Change from base Build 6e7bcf0a-1460-46ab-87e4-0e3dae4d7eb0:	-0.06%
Covered Lines:	4717
Relevant Lines:	5819

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💛 - Coveralls

[ayrat555]

a couple of comments about testing. feel free to ignore them

[vbaranov]

@zachdaniel thanks for the fix. I've installed it to stg server.

I've tested it by preliminary have been deleting indices addresses_decompiled_index, addresses_verified_index and, at least, this endpoint became to work almost instantly with offset 50 - 90. For example, /api?module=contract&action=listcontracts&offset=50&filter=4. Though, it still returns "504 gateway timeout for the limit >= 100".

As it works even without those indices (though, with a small limit of entries in the response), I would suggest to remove them from PR, because of those indices tend to increase write time into addresses table, thus increasing the number of connections to DB.

[zachdaniel]

@vbaranov Alright, I removed the temporary fetcher from this PR, so that it can safely be merged. I also double checked, and the data is fully migrated. There are no decompiled_smart_contracts that aren't marked as decompiled=TRUE in the address table, and all decompiled_smart_contracts are marked as imported=TRUE. When we're sure we are done with it, we can drop the imported field from decompiled_smart_contracts.