Move token detection to top of assets

[bergeron]

Explanation

Moves the prompt for importing detected tokens from the bottom to the top of the assets view. So that users can see it without scrolling to the bottom.

Implements https://consensyssoftware.atlassian.net/browse/MMASSETS-24

Screenshots/Screencaps

Before

After

Manual Testing Steps

Send an ERC-20 token to the account and verify the import prompt appears at the top.

Pre-merge author checklist

• I've clearly explained:
  • What problem this PR is solving
  • How this problem was solved
  • How reviewers can test my changes
• Sufficient automated test coverage has been added

Pre-merge reviewer checklist

• Manual testing (e.g. pull and build branch, run in browser, test code being changed)
• PR is linked to the appropriate GitHub issue
• IF this PR fixes a bug in the release milestone, add this PR to the release milestone

[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.

[codecov]

Codecov Report

Patch coverage: 25.00% and no project coverage change.

Comparison is base (a3a99aa) 68.25% compared to head (b9f14c7) 68.25%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #20932      +/-   ##
===========================================
- Coverage    68.25%   68.25%   -0.00%     
===========================================
  Files         1006     1006              
  Lines        40184    40183       -1     
  Branches     10742    10741       -1     
===========================================
- Hits         27424    27423       -1     
  Misses       12760    12760              

Files Changed	Coverage Δ
ui/components/app/asset-list/asset-list.js	75.00% <25.00%> (-0.76%)	⬇️

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[metamaskbot]

Builds ready [b9f14c7]

• builds: chrome, firefox
• builds (beta): chrome
• builds (flask): chrome, firefox
• builds (MMI): 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 (1626 ± 45 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	110	196	141	20	10
		domContentLoaded	1484	1816	1626	94	45
		load	1484	1816	1626	94	45
		domInteractive	1484	1816	1626	94	45

Bundle size diffs

• background: 0 Bytes (0.00%)
• ui: -4 Bytes (-0.00%)
• common: 0 Bytes (0.00%)