Functions to enable GnosisSafe app link

[vbaranov]

Motivation

Add functionality to display a link to Gnosis Safe app

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 6829890875b1916279f377d09f5523185cb96296-PR-3421

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 15 unchanged lines in 5 files lost coverage.
• Overall coverage increased (+2.8%) to 67.325%

---

Files with Coverage Reduction	New Missed Lines	%
lib/block_scout_web/controllers/chain/market_history_chart_controller.ex	1	78.57%
lib/block_scout_web/channels/address_channel.ex	2	36.96%
lib/block_scout_web/notifier.ex	2	82.95%
lib/block_scout_web/views/address_view.ex	4	83.54%
lib/block_scout_web/checksum_address.ex	6	55.56%

Totals
Change from base Build cb0d50c7d89a2bc379984769afd3b491bdbb4fe6:	2.8%
Covered Lines:	2046
Relevant Lines:	3039

---

💛 - Coveralls