Allow trailing/leading whitespaces for inputs for contract read methods

[vbaranov]

Motivation

Blockscout returns odd-length string error if a user provides trailing/leading whitespaces in input data when interacts with contract's reading methods.

Changelog

Allow trailing/leading whitespace in input data of read-only methods of contracts

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 1258d3e894ca3c1cc8a16c0c7f5622dd5cfcac00-PR-3530

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.9%) to 66.871%

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Totals
Change from base Build b59db8067b59e322a591087d46fb65593443fda8:	-0.9%
Covered Lines:	2075
Relevant Lines:	3103

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💛 - Coveralls