Fix Sushiswap LP tokens custom metadata fetcher: bytes(n) symbol and name support

[vbaranov]

Motivation

Missing token name and symbol of MKR in Sushiswap LP token

Changelog

MKR token and symbol getters have byte32 type, unlike others. This PR enables support in metadata fetcher for Sushiswap LP tokens which have bytes(n) type for symbol and token getters in token contract.

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 300b7b3866e818e09afbf11ec4b2bbec28be24c4-PR-3742

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.3%) to 64.63%

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

Totals
Change from base Build 645e3efc56a80e48cfe10536db0dbb4b218296db:	-0.3%
Covered Lines:	2105
Relevant Lines:	3257

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💛 - Coveralls