Add pool metadata display/change to Staking DApp

[varasev]

Motivation

These changes add pool names and descriptions to Staking UI. Now, if a pool has a name, it will be displayed in lists and popups instead of a short representation of the staking address. Description is displayed in Pool info popup.

Pools can change their names and descriptions through the Pool info popup as it's shown on one of the screens below.

The screenshots:

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 41ab0a23b46524ea96806a29cc5f952ad5f80613-PR-3758

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+9.5%) to 64.188%

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Totals
Change from base Build 3cc73bf223bbfa7497978b6c6578dc06ca373c95:	9.5%
Covered Lines:	2115
Relevant Lines:	3295

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💛 - Coveralls