Migrate to ex_abi 0.3.0

[vbaranov]

Fixes #1258
Fixes #3048
Fixes #3049

Motivation

Blockscout doesn't support decoding of ABI-encoded parameters of non-fixed length.

Related PR to update ex_abi library poanetwork/ex_abi#24

Changelog

• import ex_abi 0.3.0
• extend decode_result function cases
• fix tests

Checklist for your Pull Request (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 by submitting a PR to https://github.com/blockscout/docs
• If I added/changed/removed ENV var, I submitted a PR to https://github.com/blockscout/docs to update the list of env vars at https://github.com/blockscout/docs/blob/master/for-developers/information-and-settings/env-variables.md and I updated the version to master in the Version column. Changes will be reflected in this table: https://docs.blockscout.com/for-developers/information-and-settings/env-variables.
• If I add new indices into DB, I checked, that they are not redundant with PGHero or other tools

[coveralls]

Pull Request Test Coverage Report for Build d94b1255-a3b9-4206-9825-c9a6ba2f6287

• 4 of 7 (57.14%) changed or added relevant lines in 3 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.04%) to 75.075%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
apps/block_scout_web/lib/block_scout_web/views/address_contract_view.ex	0	1	0.0%
apps/ethereum_jsonrpc/lib/ethereum_jsonrpc/encoder.ex	1	2	50.0%
apps/explorer/lib/explorer/smart_contract/reader.ex	3	4	75.0%

Files with Coverage Reduction	New Missed Lines	%
apps/block_scout_web/lib/block_scout_web/controllers/chain/market_history_chart_controller.ex	2	71.43%

Totals
Change from base Build 55bc48ba-113b-4343-9240-cc046db58f23:	-0.04%
Covered Lines:	5512
Relevant Lines:	7342

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💛 - Coveralls