Reorganize staking buttons

[vbaranov]

Changelog

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 d40cd8bb0a27b335607861f79bf8d6da54fcb7e2-PR-3688

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.4%) to 64.751%

---

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 d402babe54c2e5585dc3e2ecde31626fe319e359:	0.4%
Covered Lines:	2107
Relevant Lines:	3254

---

💛 - Coveralls