chore: make account management toggles use toggle functions instead of setters

Description

Refactor to make the import accounts drawer use toggle functions instead of setters. No functionality changes with this PR.

NOTE: A bug was identified while implementing this where the toggle state from a previous chain being managed appears on the current one - this will be fixed in a follow-up PR (https://github.com/shapeshift/web/pull/6817) as it's unrelated to this.

Pull Request Type

[ ] :bug: Bug fix (Non-breaking Change: Fixes an issue)
[x] :hammer_and_wrench: Chore (Non-breaking Change: Doc updates, pkg upgrades, typos, etc..)
[ ] :nail_care: New Feature (Breaking/Non-breaking Change)

Issue (if applicable)

closes #6815

Risk

High Risk PRs Require 2 approvals

Low risk.

What protocols, transaction types or contract interactions might be affected by this PR?

Testing

Check account import toggles in the account management drawer functions as it did previously (including the toggle state bug identified above)

shapeshift / web