fix: change asset picker button to buttonbase to fix text theming

[jclancy93]

Description

The asset picker in dark mode previously showed the down icon and token symbol in their light mode variants, instead of dark mode. This is because Button defaults to the primary variant which hard codes the theme as light mode for all descendant elements. This PR changes the AssetPicker main component from Button to ButtonBase since it does not default to light mode

Related issues

Fixes: #27046

Manual testing steps

1. Change to dark mode
2. Open Send Page
3. Asset symbol and down carat should both render as white
4. Switch to light mode
5. Asset symbol and down carat should both render as black

Screenshots/Recordings

Before

After

Pre-merge author checklist

• I've followed MetaMask Contributor Docs and MetaMask Extension Coding Standards.
• I've completed the PR template to the best of my ability
• I’ve included tests if applicable
• I’ve documented my code using JSDoc format if applicable
• I’ve applied the right labels on the PR (see labeling guidelines). Not required for external contributors.

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.

[jclancy93]

All changes in this file are from running yarn test:unit --updateSnapshot

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.96%. Comparing base (ca6fd53) to head (bf7e8ab).
Report is 2 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop   #27127   +/-   ##
========================================
  Coverage    69.96%   69.96%           
========================================
  Files         1442     1442           
  Lines        50100    50100           
  Branches     14006    14006           
========================================
  Hits         35049    35049           
  Misses       15051    15051           

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[metamaskbot]

Builds ready [bf7e8ab]

• 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, 5
  • common: 0, 1, 10, 11, 2, 3, 4, 5, 6, 7, 8, 9
  • content-script: 0
  • offscreen: 0
  • ui: 0, 1, 10, 11, 2, 3, 4, 5, 6, 7, 8, 9

Page Load Metrics (1886 ± 131 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	303	2492	1805	437	210
		domContentLoaded	1526	2483	1859	257	123
		load	1560	2495	1886	273	131
		domInteractive	23	68	38	16	8

Bundle size diffs

• background: 0 Bytes (0.00%)
• ui: 60 Bytes (0.00%)
• common: 0 Bytes (0.00%)

[georgewrmarshall]

LGTM! Thanks for this @jclancy93 🙏