"Need recompile" column in the env vars table

[vbaranov]

Motivation

Some ENV vars used on the compilation time. We need to distinguish them from others.

Changelog

Need recompile column is added to the table with ENV vars.

The current list of vars that used in the compilation:
DISABLE_WEBAPP
DISABLE_READ_API
DISABLE_WRITE_API
DISABLE_INDEXER
GRAPHIQL_TRANSACTION

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
• If I added/changed/removed ENV var, I should update the list of env vars in https://github.com/poanetwork/blockscout/blob/master/docs/env-variables.md to reflect changes in the table here https://poanetwork.github.io/blockscout/#/env-variables?id=blockscout-env-variables. I've set master in the Version column.
• If I add new indices into DB, I checked, that they don't redundant with PGHero or other tools

[coveralls]

Pull Request Test Coverage Report for Build ab3cc03e-f980-4b22-a1c6-f9c404115d94

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.03%) to 79.123%

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Files with Coverage Reduction	New Missed Lines	%
apps/explorer/lib/explorer/chain/cache/transaction_count.ex	2	84.21%

Totals
Change from base Build 17850602-df8e-435c-80cf-20128ccea7eb:	-0.03%
Covered Lines:	5196
Relevant Lines:	6567

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💛 - Coveralls