Force to show address view for checksummed address even if it is not in DB

[vbaranov]

Related issue https://forum.poa.network/t/blockscout-doesnt-show-address-info/2843

Motivation

In the described in the link above case, a developer uses a link to Blockscout address page and if there were no transactions with this address, we show 404 page, but instead, I think we should display an address view, if this address is checksummed.

The possible use case can be if the user sends a transaction from a dapp/wallet to an address, which never has in/out transactions in the blockchain and w/out waiting of confirmation goes to Blockscout to see the balance update. To show address view with a zero balance is less confusing than to display 404 page.

Changelog

Enhancements

8dc5f00 - Address view for checksummed address is allowed
1c67e56 - Hide Last Balance Update in address view if there is no fetched_coinbalance_block_number, because, I suppose, we don't want to trigger on-demand balance update if the address has no transactions yet

Bug Fixes

a789586 - chore, fixing of expected action/2 to return a Plug.Conn, all plugs must receive a connection (conn) and return a connection, got: {:error, :not_found} error when opening page like http://localhost:4000/address/{address_hahs}/coin_balances with inexisting address. This related error was detected while working on this PR.

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 a7eccdb5-57b5-475f-8c5c-cfaf298f9b08

• 2 of 11 (18.18%) changed or added relevant lines in 2 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.1%) to 79.289%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
apps/block_scout_web/lib/block_scout_web/controllers/address_coin_balance_controller.ex	0	2	0.0%
apps/block_scout_web/lib/block_scout_web/controllers/address_transaction_controller.ex	2	9	22.22%

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 91a900db-612f-42a8-b953-ce8e031ea189:	-0.1%
Covered Lines:	5149
Relevant Lines:	6494

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💛 - Coveralls