Fix performance of coin balance history chart

[vbaranov]

#1946

Changelog

Create a proper table to get data for coin balance history chart:

\d address_coin_balances_daily;
                    Table "public.address_coin_balances_daily"
    Column    |            Type             | Collation | Nullable |    Default
--------------+-----------------------------+-----------+----------+---------------
 address_hash | bytea                       |           | not null |
 day          | date                        |           | not null |
 value        | numeric(100,0)              |           |          | NULL::numeric
 inserted_at  | timestamp without time zone |           | not null |
 updated_at   | timestamp without time zone |           | not null |
Indexes:
    "address_coin_balances_daily_address_hash_day_index" UNIQUE, btree (address_hash, day)
Foreign-key constraints:
    "address_coin_balances_daily_address_hash_fkey" FOREIGN KEY (address_hash) REFERENCES addresses(hash)

and adding a logic of filling it with the data. Retrieve data for coin balance history chart from this table. After this PR, the number of days to display at the coin balance history chart can be configured via environment variable COIN_BALANCE_HISTORY_DAYS

Related PR to add COIN_BALANCE_HISTORY_DAYS env var to the list blockscout/docs#20

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 e908e697-779e-4dca-a320-c85757576711

• 114 of 135 (84.44%) changed or added relevant lines in 11 files are covered.
• 4 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.2%) to 75.155%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
apps/indexer/lib/indexer/block/realtime/fetcher.ex	10	11	90.91%
apps/indexer/lib/indexer/fetcher/coin_balance_on_demand.ex	12	13	92.31%
apps/explorer/lib/explorer/chain/import/runner/address/coin_balances_daily.ex	13	18	72.22%
apps/indexer/lib/indexer/transform/address_coin_balances_daily.ex	32	46	69.57%

Files with Coverage Reduction	New Missed Lines	%
apps/indexer/lib/indexer/fetcher/coin_balance_on_demand.ex	4	85.37%

Totals
Change from base Build 22318daf-e286-45a5-bab3-923eb1ed4ab4:	0.2%
Covered Lines:	5835
Relevant Lines:	7764

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💛 - Coveralls

[leeoniya]

@vbaranov if you want to improve the frontend chart performance, too you can try using uPlot instead of Chart.js. Phoenix LiveDashboard uses uPlot for their real-time metrics panel.

/shameless plug :D

[vbaranov]

@leeoniya performance comparison of chart libraries looks promising! Definitely I should give it a try. Thanks for pointing me out.