UX: Multichain: Add separator under 'View on Explorer'

[darkwing]

Description

This PR adds a separator to the Multichain global menu under View on Explorer

Manual testing steps

1. Open the Global Menu
2. See the separator between View on Explorer and its next menu item

Screenshots/Recordings

Related issues

Fixes: #21220

This issue also references the position of the Account Picker but that is addressed in #21220

Pre-merge author checklist

• I’ve followed MetaMask Coding Standards.
• I've clearly explained:
  • What problem this PR is solving.
  • How this problem was solved.
  • How reviewers can test my changes.
• I’ve indicated what issue this PR is linked to: Fixes #???
• I’ve included tests if applicable.
• I’ve documented any added code.
• I’ve applied the right labels on the PR (see labeling guidelines).
• I’ve properly set the pull request status:
  • In case it's not yet "ready for review", I've set it to "draft".
  • In case it's "ready for review", I've changed it from "draft" to "non-draft".

Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[metamaskbot]

Builds ready [7edf1e1]

• builds: chrome, firefox
• builds (beta): chrome
• builds (flask): chrome, firefox
• builds (MMI): chrome, firefox
• builds (test): chrome, firefox
• builds (test-flask): chrome, firefox
• build viz: Build System
• mv3: Background Module Init Stats
• mv3: UI Init Stats
• mv3: Module Load Stats
• mv3: Bundle Size Stats
• mv2: E2e Actions Stats
• code coverage: Report
• storybook: Storybook
• typescript migration: Dashboard
• all artifacts
• bundle viz:

  • background: 0, 1, 2, 3, 4
  • common: 0, 1, 2, 3, 4, 5, 6
  • content-script: 0
  • contentscript: contentscript
  • disable-console: disable-console
  • inpage: inpage
  • policy-load: policy-load
  • sentry-install: sentry-install
  • ui: 0, 1, 10, 11, 12, 2, 3, 4, 5, 6, 7, 8, 9

Page Load Metrics (1316 ± 347 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	85	200	104	27	13
		domContentLoaded	70	193	100	27	13
		load	81	2213	1316	723	347
		domInteractive	70	193	100	27	13

Bundle size diffs

• background: 0 Bytes (0.00%)
• ui: 135 Bytes (0.00%)
• common: 0 Bytes (0.00%)

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (f80569a) 68.61% compared to head (7edf1e1) 68.61%.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop   #21223   +/-   ##
========================================
  Coverage    68.61%   68.61%           
========================================
  Files         1017     1017           
  Lines        40814    40814           
  Branches     10900    10900           
========================================
  Hits         28002    28002           
  Misses       12812    12812           

Files	Coverage Δ
...i/components/multichain/global-menu/global-menu.js	62.07% <ø> (ø)

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