Raw trace of transaction on-demand

[vbaranov]

Motivation

We will start to ignore first traces from #3000 in case of Parity variant. Thus, we will not store them in the DB in order to shrink occupated space. In order to not break raw trace feature in Blockscout it is implemented to get transaction's raw traces on demand. Actually, the first trace will be fetched on-demand from the archive node once anyone opens the /raw_trace page of transactions for the first time and this first trace saved to the DB. And raw trace will be collected from all internal transactions from the DB and displayed on the page. If the first trace already exist in the DB, application will no request the node again in order to fetch it.

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 42a158d6-28a5-4ddf-8e27-6bf0804547b6

• 43 of 78 (55.13%) changed or added relevant lines in 6 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.1%) to 75.075%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
apps/ethereum_jsonrpc/lib/ethereum_jsonrpc.ex	0	1	0.0%
apps/indexer/lib/indexer/fetcher/internal_transaction.ex	0	3	0.0%
apps/ethereum_jsonrpc/lib/ethereum_jsonrpc/parity.ex	16	20	80.0%
apps/explorer/lib/explorer/chain/import/runner/internal_transactions.ex	0	4	0.0%
apps/explorer/lib/explorer/chain.ex	27	38	71.05%
apps/block_scout_web/lib/block_scout_web/controllers/transaction_raw_trace_controller.ex	0	12	0.0%

Files with Coverage Reduction	New Missed Lines	%
apps/block_scout_web/lib/block_scout_web/controllers/chain/market_history_chart_controller.ex	1	78.57%

Totals
Change from base Build 64e3f4f0-9d21-4c8c-86e1-46c9589b45a5:	-0.1%
Covered Lines:	5482
Relevant Lines:	7302

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💛 - Coveralls